For the most part, this extension is amazing, definitely helps with combating YouTube's auto quality setting too.

This extension is missing out on a lot of the updates from its GitHub repo however.

If anyone is coming across an issue where you can't re-enable comment avatars try this:
#1: Go to "about:devtools-toolbox?id=%7B3c6bf0cc-3ae2-42fb-9993-0d33104fdcaf%7D&type=extension"
#2: Click "Storage" from the top if it hasn't been selected already
#3: Open "Extension Storage" from the left side
#4: Click on the first result
#5: Click "Filter Items" and type "hide_author_avatars",
#6: Right click on the first result and click "Delete hide_author_avatars"
This should bring back comment avatars (you may need to reload existing YouTube tabs)
You do need to delete the key since setting the value to "false" doesn't work on this particular version of Improve Youtube (3.935).