@mcc @brandon At the least, I'd check the LibreWolf config page and think about "Silently block canvas access requests" and "Enable letterboxing" which are under the ResistFingerprinting one and one of them might be turned on by default? (Don't entirely remember.)

The first (block canvas access) suppresses warnings that a site is requesting to access your canvas and those are useful to know if something might break (it usually won't, but you can hit a button to dismiss it permanently for that site). The second locks LibreWolf to only display at common resolutions no matter what your window size is and put padding around it for the rest of the window. That one's too much for even me.