Cat pee's against the litterbox edge

I a questioning stuff and honestly idk what to do anymore lol

My cat is...smart but very dumb at times. Often has issues with going to the litterbox.

I dont mean as in she cant do her business, but i mean as in...she seems to be dumb enough not to do it properly?

Example one, the main issue i am dealing with. She pees at the opening of the litterbox, against the edge. Yesterday she did this and pee was all over the edge and on the litterbox mat we have. That thing is smelling horrible and even after cleaning the stench stays, so i just put it outside so it can be thrown away.

She likes to pee against the walls of the litterbox litterbox. I dont mind this at much, but i am honestly clueless as to why she does this.

Specifically because of these issues, we got a BIG high wall litterbox when we first got get back in 2023, because she first kept peeing outside/ on the edge of open and closed litterboxes.

Litterbox in question : Modkat flip litterbox. We dont use the outlining because that breaks too fast with out cat who likes to scratch against the walls.

We clean the litterbox daily. Daily a tiny bit extra filling for a fresh feel. We deep clean it too.

She isnt big, altho for a female cat she's a tiny bit bigger then most female cats that my vet sees.

Anyone else has clues on why she does this?