I'm not a professional by any means, however, from what i understood, Painwheel is generally considered ''low tier'' by many due to some factors:
1. Although she possesses high damage potential, she has one of the lowest HP of the cast.
2. She has a rather poor ground movement, a slow dash, and only one air jump, therefore she is very susceptible to be trapped.
3. She lacks a fully invincible reversal move to get out of pressure.
4. And she is considered to be very difficult to mastery by many.
But even so, that doesn't exactly mean she is straight up ''trash''. For example, she has a strong armor and, as i mentioned earlier, can deal massive damage, but the path of mastering her can be way more challenging than most of the other characters. In the end, if you are already comfortable and want to keep playing with Painwheel, just keep playing with her. You are the one who is playing after all lol.