ActivityPub has fostered a social web for millions of people. To grow, some developers believe it needs improvement. These are their efforts.
ActivityPub has remained the dominant Fediverse protocol over the past few years. In that time, many bright ideas have come on how to improve the spec. Here's where those efforts are today.
One thing I miss in activitypub is a verification system. This is most important for deletion. For example, when something is deleted on one instance, there's no way of knowing for sure if it will be deleted from other instances as well. An instance being down or malfunctioning can cause deletion to fail with no way to know* and try again for op.
*To know one would have to check every single subscribing instance. Trying to delete an already deleted item is obviously impossible
there's no way of knowing for sure if it will be deleted from other instances
You can't be sure if something is deleted, because there is no way to prove you don't have something.
However, if you just want to check if the instance claims to have deleted something, you could probably just perform a GET request for the specific object as defined in the activitypub spec.