Why do certain character sequences get replaced by icons?

Hi All, so my problem is that when I enter text some character sequences cause icons to be inserted automatically. I’ve made a screen recording of the behavior to help better your understanding of what is going on. Here is a link to the recording.

The behavior happens on both the mac desktop and web versions.

I may have accidentally set a parameter without knowing it (fat finger problem :grimacing:). Thanks for your help.