The only person I’ve ever seen get fired due to incompetence was a mis-hire. Someone someone with junior level skills had the title of senior and it took them weeks or months to do basic tasks. They also had poor people skills. I honestly just don’t know how they got hired.

If you’ve got the dev skills that’s what matters the most. Leaning internal systems and dev processes is stuff you will pick up with time.

If git is slowing you down - invest your off hours in learning git. Likewise for anything else.