I heard about some relays possibly enforcing this. I haven’t tested it out myself.

Upon finding this out one of the first things I did was write a relay proxy that enforced it (helped me learn about the protocol)

The major downside of this is if you’re looking to migrate your signed events to another relay.

The relay just sees it as signed events and would reject it as being too old.

Future events I could see less of a need for. Maybe clients could be more of the guard rails on that since something posted in the future shouldn’t make any sense and should be ignored.