This started happening with the season 8 patch. At first I assumed Blizzard had set a souvenir to take over one blank space on the emote wheel, as a new default, and it was selecting ‘mutton chop’ for everyone as that is at the top of the souvenir list.
Not wanting anything on the wheel that I could accidentally press, I simply replaced it on the emote wheel for every character (tedious) with regular emotes, and carried on playing.
However, today when I started playing, I saw that ‘mutton chop’ was, again, on my emote wheels, this time actually taking the place of emotes I had selected. I have several characters with all four slots assigned, and yet today, ‘mutton chop’ was there, taking over the right-hand slot.
Clearly Blizzard wants to push souvenirs because they’re a cheap way of padding out the battle pass, but nobody actually uses them. However, forcing them onto the wheel, when a player has specifically assigned wheel slots to other things, is simply plain wrong. At this point I am being charitable and assuming it is a bug which simply needs to be stopped, but if this is intentional behaviour then it needs to be stopped and apologised for.