Bare notice [1] should take zero time to implement. Just show users the true status [2]. Reasons for removal can come later. Right now everyone is still in the dark, and it's a year after acquisition.
It is way too easy to shadowban on social media. Some mods are not only brazen about shadowbanning, they also suggest digital IDs would be a substitute [3].
However, once we move to digital IDs, I doubt shadowbanning will go anywhere. Just like we pay for ads on cable TV, shadowbanning will always be a thing. Don't fall for the line, "we'll stop when X happens."