Any accordion players? Proper accordion adjustment?

I’m not a professional, but I played the accordion for 5 years and yes, both straps should be fairly tight (you tie the right side of the instrument to your body, and move the left one away from you). It’s also important to tie the wrist strap quite firmly too (depending on your model of course). Mine had some sort of screw on top that you could easily turn with your hand. If it’s too lose you waste too much effort trying to open and close the accordion so obviously your left hand won’t be stable enough to play the chords.

Thank you @Jack79! I think my wrist strap is too loose, I’ll try that first!