Study a Tactics book. Online tactics like trainer and tempo looks fun and gratifying with its inflated ratings but you learn less. At your level I recommend Winning Chess Combinations by GM Seirawan.
how to study skills?

https://chessmood.com/blog/how-to-improve-your-tactical-vision I brought a very good article for you
hi, this is my first time posting
Always i've had the doubt about how to improve my tactic skills on a deeper way. It's obvious that you can achieve this goal solving a lot of puzzles, but if you stop doing, the skill could decrease or dissapears (at least at my level), and this is what i don't want.
my point is: exist a a deeper way of learn tactics? For example: you can learn the idea of certain mates as king + queen (attack as knight), king + rook (cut space to opponent's king, help rook), two bishops vs king, etc and you dont need to memorize the moves, only understand the "essence" of the mate to apply on a game.
How to study tactics on a way that recognize certain patterns could be easier to me?
Or i am wrong? i'm afraid that tactics could be as train on a gym and if you stop doing, the ability will be lost.