Hilton is also extending free night expiration. From email just now:
[QUOTE]For all unexpired Weekend Night Rewards as of March 11, 2020, and all new ones issued until August 30, 2020, we are extending the expiration date through the end of next summer (August 31, 2021). There is no need for you to do anything, as your certificate(s) are being automatically updated in our systems.[/QUOTE]

So just hyatt and ihg holding out.