Firefox not showing summoner thumbnails

[cpsilent]

I'm using Firefox 90.0 on Kubuntu 20.04 LTS 64 bits and the videos playing for the summoner thumbnails never had displayed on screen correctly. For example, I watched on a youtube video that this should be seen like this:

However, in my browser the thumbnails are displayed like this instead:

I already disabled my ad blocker for splinterlands.com but it still shows no graphics for the summoners.

I hope this issue is in the right repository. Thank you!