MacBook Pro 14" (M3 Max, 2023) - Firefox 145.00
When playing a YouTube video, moving the mouse cursor to a video thumbnail causes the currently-playing video to visibly darken while the mouse pointer is hovering over a video thumbnail.
Behavior does not replicate on Safari Version 26.1 (21622.2.11.11.9) or Vivaldi 7.6.3797.63 (Stable channel) (arm64).
The only currently-running extensions are uBlock Origin and Bitwarden.
