I (think) 'm better than 400 elo, but i still here

Why am I still at 400 elo (win or lose some online matches) if I can easily win Maria bot (1000 elo)?

The bots rating doesn't match human strength. Most people can beat bots much higher than their actual rating. Just looking at your past 7 days of games, you're win/loss is trending downward from where you were 7 days ago. I didn't check but do you resign games? My suggestions, do blunder checks every move, don't resign, follow opening principals (i.e control the center, castle early, activate your pieces, don't move the same piece twice in the opening if you can help it). Work on middle game and end game puzzles in your spare time.

Bots are overrated (at least lower rated bots). A well known problem that chess.com just won't fix.

Look at your recent games to identify patterns in your mistakes.