Me too. I check (ir-)regularly if any instances got defederated.
But I think even if it happens, they would inform us. Communication from the admins regarding changes seems very good.
EDIT: You can check it for yourself over here. It doesn’t show exactly which instances are blocked, but it helps.
EDIT 2: Better check VLemmy’s instance page directly. Blocked instances should be listed in there, if there will be any. Last link led to outdated information.