What problem are you trying to solve?
After recently upgrading to .NET 6, there's a new analyzer prompting you to convert dict.Keys.Contains("foo") to dict.ContainsKey("foo"), but that's not supported by EF Core, so a quick refactor can have nasty consequences.

Describe the solution you'd like
Can dict.ContainsKey be supported?

I could probably help out with some direction.

(didn't see any previous issues actually ask for this, sorry if it's been previously rejected)