It appears that some countries no longer allow the use of postage stamps on mail (even though they may still produce stamps), for example:
-Pakistan (Pakistan Post) announced around May 2020 that stamp on INTERNATIONAL mail from Pakistan to other countries is no longer allowed (so it seems only stamps on domestic mail are allowed)
-Iran (Post Company of the I.R. Iran) no longer allows stamps on any mail even though it still produces them
Have collectors heard of other countries not allowing stamps on mail anymore?