Nextcloud 15 - Avatars reverted to generated ones after update

Just upgraded my nextcloud box from 14.0.4 to 15.0.2. Everything went smooth but I noticed that avatars for all users are reverted to the ‘generated’ ones. I did re-scan app data files but does not seem tfix it. I can see avatars in the appdata directory. Upon uploading avatar again, everything seems to work and I can see my avatar as well as others can see it when sharing etc.

Did anyone encounter this issue?

Just upgraded from 13.0.4 -> 14.x -> 15.x and had the same problem, with the same behaviour of the avatar data being stored but not served.