Hey there, this writeup should provide you most of the answers: Concurrency in Swift 5 and 6
Short version: we're on the road to Swift 6 which will enable all those checks and make them hard errors. In Swift 5.5 not everything is a hard error yet, but you can opt into more aggressive checking with optional compiler flags (e.g. -warn-concurrency enables Sendable checking).
Hope this helps!