Since a year ago, does it take more skill to hold the same rating?

I used to be rated 1450ish. I left chess for at least 6 months, though I was studying much less even 6 months before that. I came back on here, and now I can't break 1350, and am currently 1300.

Is it more likely that the other 1300 players have just been studying and raising the bar for that rating, or is it more likely that I just lost a solid 100+ off my skill level?

You're just plain rubbish. That's all.

No, well I've found that depending upon which time of day you go and play the games, the quality of certain ratings is different. So, maybe you played at a different time of day? The ratings on chess.com aren't all that reliable though. My suggestion is to just keep on playing and you will eventually become the rating you were before if not more than that. Also bear in mind that if you play on your phone that is considerably harder, in my mind as you can hardly see the pieces!

Sure, there's always going to be ratings inflation.  Though this might point to other factors:

There is a long-term pattern database that your brain never erases....trouble is : it takes a lot of practice + burn-in time to make sure that new patterns go in and STAY IN!!!

These concepts/positions that have burned into your retinas pretty much define the "lowest" rating level you will play at, life long! (unless old age starts messing with brain function!)

Depending on your skill level, can either just be basic mates and tactics or something far more complex and nuanced.

Not playing for 6-months to a year will have you showing rust at seeing tactical shots and your time management/nerves will be less reliable than it used to be ... though it really comes down to how much your "know it cold" brain absorbed when it was getting fed chess regularly :)

A lot of my breaks from chess has me forgetting things that were not practiced regularly enough to become "permanent" ... that and missing shots / playing too fast/too slow had me slip in playing strength.

I think it was closer to two years ago, but there seems to have been some adjustment in the rating formula. My peak rating in several categories almost seems unattainable.