This started happening on my desktop teams clients using the NEW teams (btw, terrible name.. should be simply versioned... is the next one going to be called "Newer New teams"?
I don't know if others are having the same issue.. but most others show all the icons, and not experiencing the problem I have.
Once, I was able to do the App Advanced settings and used "Reset" and "Repair". it worked for a little bit but went back to removing most of the chat icons again.
I have like 10 chat icons missing. I only now see: format, emoji, loop components, and "actions and apps" which doesn't show any options for GIF or some of the other missing icons.