Maybe because you aren’t feeling well when you play as black? Or maybe because you are confident that you will lose as black, and you really lose?
11 losses in a row as Black

Maybe because you aren’t feeling well when you play as black? Or maybe because you are confident that you will lose as black, and you really lose?
I wasn't feeling well on the sixteenth and I lost both games (technically one was a draw) I played that day as black, so that it is a possibility. The other nine games I was fine.
Poor confidence in playing as black could make me play worse to a certain extent, but I have a hard time believing it's the only thing keeping me from winning a game. I like to observe trends, so when I see an additional loss as black that gets added with the now more than 10 loses, I get discouraged that I'd win the next game. It also doesn't help that I play as black a little more than white and I can see that I lose twice as much as black as I do white.
So if it is confidence alone, all I would need to do to start winning again is change my attitude and I should find some success.

Here is my twelfth consecutive loss as black. I go in with confidence, seeing that my opponent has less ELO than me and I have a good opening. By move 23, we have equal material and no one really is winning. After white captures pawn with 23. cxd5, I have two choices. I either trade queens or I take what seems to me a free pawn on a5. In my mind, I calculated I could gain the pawn on e5 with my bishop but in the end, the amount of material gain would be the same for the both of us so either choice seemed ok to me. The problem is 24. d6+ ultimately sets up for a checkmate several moves ahead that I could not see.
So, what gives? I'm anticipating my opponent's next move, I have good opening principles, I'm analyzing my mistakes in previous lost games, I'm going into games with greater confidence, etc. Why am I still constantly losing as black?

In the above game, your king has been left pretty exposed by not castling, and then opening up the pawns in front of it with 21. fxe5. This is aside from the fact you were hanging your queen, and where Qxb4 would have solved that, gained a pawn, and opened up the opponent. So really the checkmate issue could have been avoided before move 23 with more careful play. The castling thing stemmed from 8. g6 which didn't achieve anything. General advice is not to move those three pawns unless you really can't help it. Sure hindsight is 20-20, but the king is the most important piece. Exposing it for short-term gains may prove costly in the long-run.
There are plenty of posts of tips on how to play as black for x rating range etc which I'm sure you can review. Recurring themes will be focusing on not making mistakes, as whoever blunders the most will lose. And also to learn a few standard responses to common white openings such as d4/e4 so they don't control the center, main lines, lots of space etc. As you've said, anticipating what the opponent will do next is critical. If you've got the hang of guessing their next move, try adding another move onto that.
Unrelated, I found this video pretty helpful: https://www.youtube.com/watch?v=SXrKRA_KZ5k

I wanted to castle but I blundered with 8 .. g6. Doing it queenside wouldn't give my king much protection but I'll keep those pawns in mind.
I'll take a look at the video, too.

I suggest playing the Viznik Variation as black. It's a variation of the Scandinavian Defense, and there's accepted and declined versions of it. It's a dominate opening as black in response to e4. I am undefeated with it in rapid!
Here's some info the Viznik Variation (SDVV):
https://www.chess.com/clubs/forum/view/viznik-variation-g6-line-is-fischer-approved
https://www.chess.com/clubs/forum/view/the-viznik-variation-works-to-almost-mint-perfection
Here is my twelfth consecutive loss as black. I go in with confidence, seeing that my opponent has less ELO than me and I have a good opening. By move 23, we have equal material and no one really is winning. After white captures pawn with 23. cxd5, I have two choices. I either trade queens or I take what seems to me a free pawn on a5. In my mind, I calculated I could gain the pawn on e5 with my bishop but in the end, the amount of material gain would be the same for the both of us so either choice seemed ok to me. The problem is 24. d6+ ultimately sets up for a checkmate several moves ahead that I could not see.
So, what gives? I'm anticipating my opponent's next move, I have good opening principles, I'm analyzing my mistakes in previous lost games, I'm going into games with greater confidence, etc. Why am I still constantly losing as black?
There won't be a thirteenth.
You finally broke the streak.
Play longer time controls like 30 mins as you will get a lot of time to think and move main thing is try not to blunder simple mates or any pieces good luck with that!. I can only give you some advice but it is on you maybe
try taking a break it would be helpful.

Here is my twelfth consecutive loss as black. I go in with confidence, seeing that my opponent has less ELO than me and I have a good opening. By move 23, we have equal material and no one really is winning. After white captures pawn with 23. cxd5, I have two choices. I either trade queens or I take what seems to me a free pawn on a5. In my mind, I calculated I could gain the pawn on e5 with my bishop but in the end, the amount of material gain would be the same for the both of us so either choice seemed ok to me. The problem is 24. d6+ ultimately sets up for a checkmate several moves ahead that I could not see.
So, what gives? I'm anticipating my opponent's next move, I have good opening principles, I'm analyzing my mistakes in previous lost games, I'm going into games with greater confidence, etc. Why am I still constantly losing as black?
The answer is simple: play the Viznik Variation

I've seen some of your games, and you aren't a bad player. You are probably uncomfortable yet with the 10 mins time control. Why don't you try something like 15'+10" or 25'+10"?
This will certainly help you blundering less.

Here is my twelfth consecutive loss as black. I go in with confidence, seeing that my opponent has less ELO than me and I have a good opening. By move 23, we have equal material and no one really is winning. After white captures pawn with 23. cxd5, I have two choices. I either trade queens or I take what seems to me a free pawn on a5. In my mind, I calculated I could gain the pawn on e5 with my bishop but in the end, the amount of material gain would be the same for the both of us so either choice seemed ok to me. The problem is 24. d6+ ultimately sets up for a checkmate several moves ahead that I could not see.
So, what gives? I'm anticipating my opponent's next move, I have good opening principles, I'm analyzing my mistakes in previous lost games, I'm going into games with greater confidence, etc. Why am I still constantly losing as black?
Your opening play is not bad. You have maintained a healthy pawn center and developed pieces centrally. The idea with f6 was not good. Your opponent also made a mistake castling queen side as his q side structure was quite bad. You should have kept your king safe and started collecting weak pawns around his king.
Within the past 20 days, I've played as Black 11 times, with a win/loss ratio of 0/11. I've made good progress in puzzles and practiced as Black against the bots and every week. I also do a lesson every week. I don't know why I keep doing so poorly compared to White. As White, I win half the time, but as Black, I'm guaranteed a loss the moment my opponent makes a move. I've tried studying tactics and analyzing my past games to see where I make mistakes. I don't think it's just bad luck or else I'd have at least one win within the past 20 days.
Besides all of this, can anyone encourage me with some tips that I haven't used yet? The suggestions in the past have been fine but I'm not seeing any progress while I'm playing.
Thanks in advance.