Hi i have been getting this lots lately too. Have finally managed to get a video of it happening as it is not consistent when it happens.
For me, this happens mainly in pixel persona (but has occurred with vector brushes). I add new pixel layer, scroll through to the brush i want start to use it and crash.
It seems to be imported brushes are the worst. I’m using some from Frankentoon but it has happened with Daub brushes too. I have hard reset. Deleted brushes/reinstalled and it still happens.
You may also see there is a lag when scrolling though brushes to show the correct brush style (they change to catch up?).
I am using 9.7 iPad Pro currently 15.5. I know 15.6 has been released but i doubt it is this as it happened during previous iOS software. Affinity is up to date too.
Please see video attached. I think I have covered everything but anything else I hope you can get it sorted!
IMG_1232.MOV