Indeed, well done!
I have/had exactly the same issues with gripping too hard. One thing @Gio and @JoshFossgreen suggested that worked well for me was at the beginning of each practice session, just fret a note very slowly and softly, starting with no pressure and increasing pressure until you get a clean note. notice how little pressure it actually takes to get a clean note. Then just do this slowly for a couple minutes, playing some notes as lightly as possible. Do this every session, speed up slowly.
Another thing I read online to try is fret some notes for a few minutes without using your thumb at all. Don’t touch the back of the bass, just fret notes softly using only your fingers.
These things helped me. I still death-grip sometimes when playing fast but I am improving.
Here’s where I asked about it: