In my case villagers lose their minecraft:job_site memory when they level up. As far as I can tell the green workstation claiming particle effect also periodically appeared despite them not gaining a new job site.
Edit: Looking into it more, I can't figure out the exact trigger. Turning villagers into zombie villagers and curing them also made some lose their job sites but others keep them.
Had the same issue on a server on the same snapshot (20w21a), this crash happens when I travel a long distance in the overworld with an elytra. Attached crash report:
In my case villagers lose their minecraft:job_site memory when they level up. As far as I can tell the green workstation claiming particle effect also periodically appeared despite them not gaining a new job site.
Edit: Looking into it more, I can't figure out the exact trigger. Turning villagers into zombie villagers and curing them also made some lose their job sites but others keep them.