When adding new avatars (users that join a Twitch channel) they were placed in front automatically by default but that could overlap the (highlighted) text and made it harder to read so now whenever new avatars are adding they are by default placed in the back and when they are chatting they are placed in the front. This way the chat will be much easier to read.
The image below shows that another avatar overlaps the avatar that just said something in chat. (green color is latest chat message)
Fixed with latest message + avatar in front, then older avatars that have said anything, then rest of the avatars and newly added avatars are added in the back.