I'm 1400 as well.
Endgames. I wish I was good at endgames. Often, the engine tells me after the game that I have played really well throughout most of the game and then if my opponent has the sense to simplify the position down to an endgame, It tells me that I have made very questionable decisions.
I'm also particularly weak when it comes to defending against passed pawns.
I've been meaning to study the games of Jose Raul Capablanca for ages now but I never get around to doing it. It might not mean much coming from me but I think attempting to understand his endgame capabilities would be a significant advancement.
Good luck.
when i still played actively i threw an obt game v 1500 uscf bruh in endgame
💀 was up a queen
i hate endgame so much
just do the lessons in order.