Hi

What is the version number of the copy of Firefox for Android that you have installed?

Are you are to provide a full screenshot of your phones screen showing the thumbnails?

I don't know how to see that number, so here is a screenshot from "about Firefox" and another screenshot from Yandex image search

What level of Enhanced Tracking Protection do you have set?

Do you have any add-ons installed in Firefox for Android?

the enhanced tracking protection is standard (default) and i haven't installed add-ons yet

Please can you share the full URL of the website that you are trying to view.

it occurs on Facebook, Google, Yandex Image Search, Twitter and if I check in another pages that content images and/or thumbnails it probably occurs too

you khow what?? you are not helping at all, I better use another browser and I forget this thing exists

Ok, thank you for your feedback.

If you would like a hand with this, please can you confirm if you have any antivirus or security apps on your device.