I can receive photos just fine, but when I try to send them (GIF or JPG) the recipient either gets nothing or gets a big block of what looks like HTML. This is a new development that I just noticed today.
I haven't sent MMS in 10 years for sure. There are so many other ways to talk to Android users, like Signal, Telegram, Whatsapp, Facebook Messenger, you name it... but I will not be using a technology from 2002 to send a highly compressed potato quality image to my friends 😉
Also, could it be that your (or your recipient's) carrier discontinued MMS? My carrier (Swisscom in Switzerland) announced that MMS will no longer work on their network starting January 10th 2023.