Is it a secret or something?
no i pretty much told you that its might be just switching the loop-single-topic.php file in your child theme with the original bbpress plugin version if you wanted the smaller avatars.
if it still looked weird the rest would’ve been just fixing a couple of lines of CSS
to completely remove them you would need to hand me a link to your site and I’ll give you a little CSS which will allow you to remove them.
you can also just remove the avatars with PHP
but just adding this code should work on an original bbPress loop-single-topic template.
.avatar-14 { display: none !important; }