iOS gets wonky as hell once you get under 1GB of storage. You’ve probably already done so at the advice of others, but going forward be it this phone or future ones try and keep it above one GB (or for safety, a few GBs) remaining. Same goes for things like laptops and desktops as well. You’d think remaining storage wouldn’t have such adverse affects but modern devices cache so much to the internal storage that OS’s invariably start acting up once it has no more space to do so.