I need your honest opinion!

Hi everyone first-time betta owner here. I am concerned about my betta. This was her when I first got her and now this is her 6 months later.

• It’s a 20-gallon tank with 8 neon tetras and 6 Corydoras. She’s not aggressive and doesn’t mind the tank mates.

• She always hides and doesn’t swim around and her fins don’t look good.

• The water is in perfect condition. I test it biweekly

• She has plenty of places to hide and live & silk plants.

• The temperature is always at 78.

• I change water every week 25%

I need your honest opinion because it’s my first time and idk what I am doing wrong. Or it might just be a genetic issue due to breeding? Please help!

Ty in advance ☺️