May I know if the Website Link Previews is enabled in Account Settings > Display > Website Link Previews for the affected user’s account as well? Since you mentioned the following, I just wanted to be sure:
If the issue is happening to every user, can you please confirm if there has been any changes on the network level that might be blocking your session to reach out to the gfycat server?
Run the following command to confirm on this:
Ahmad-Danials-MacBook-Pro:~ ahmaddanialmohammad$ echo | telnet gfycat.com 443
Connected to gfycat.com.
Escape character is '^]'.
Connection closed by foreign host.
Also, please check the
mattermost.log for error messages related to gfycat. Thanks.