Joplin for Android v3.0.8 was just released and fixes a performance issue related to many nested notebooks. If there are a large number of nested notebooks, then this issue might be fixed in v3.0.8.
Alternatively, in the past, the slider component used on some settings pages has caused crashes on some devices (issue, upstream issue). We applied a workaround, but it's possible the workaround needs to be re-applied or adjusted.