For anyone who is interested in this - it is great and you can export all your Apple notes.app stuff (inc images) with the mac app Exporter, then import into Bear.app.
I can't recommend Bear enough if you're using all Apple devices. I've used many note taking app but Bear is the only thing that gives me Markdown note taking + not getting in my way of writing. I especially like the infintely nested tag of Bear, such a time saver when you can drop a #hastag/anywhere/with/inifitely/nested/hierachy .
Disclamer: I'm not affliated with Bear in anyway, just a happy customer.
Bear uses iCloud storage which has on multiple occasions trashed people's data during iOS beta periods. It's not "Bear Sync", it's just another iCloud beta sync problem. If you value your data, don't use iOS betas. It's that simple.
If they had the choice, many developers would disable their apps on beta devices because of issues like yours.
I used to use bear too until I discovered notion.so, now I use nothing else (also not affiliated with Notion or Bear, but used to use bear for everything)
* https://bear.app/