.Net 3.0 has gone through about a dozen preview releases and the last 4 have a go-live production license. It's much better tested than the old .NET Framework with its monolithic releases.
I can at least name two bugs.
both bugs do not apply to everybody and one is fixable with some additional code.
I reported both in preview9, one should be included into 3.0 but was not.
the other will be fixed in 3.1:
- https://github.com/aspnet/AspNetCore/issues/13696 - https://github.com/aspnet/AspNetCore/issues/13715
(Edit: corrected first link)