> I agree that many of MS’s “open source” libraries (eg EF, OData) are half-assed, badly run projects.

Just as a counterpoint to this, I have found Entity Framework (Core) to be an extremely nice and very productive dev experience, with a lot of constant improvements in every release. MS don't always get it right, but I definitely wouldn't call EF a "half-assed, badly run project" by a long stretch. (Though there are probably other MS projects I might be more inclined to describe as such!)

That said, they were pretty brutal in cutting off legacy support for those still using .NET Framework and trying to migrate. Through luck, I didn't have to suffer too much pain, but the migration story from .NET Framework to the new world of .NET (including EF to EF Core) has not been the smoothest for some scenarios.