This started happening to me a little while ago and slowly got worse and worse (re initializing devices didn't stick and I even went as far as buying a new ZigBee stick). While it ruined a weekend, I migrated everything to Z2M. To date, not a single device has dropped from the network. Zha has definitely borked something.
I've tried reporting issues before with other HA things, but have always got the "not my problem" treatment from frenck, so I just went straight to migrating to Z2M instead of bothering this time lol