https://www.techradar.com/news/mozilla-claims-google-has-made-youtube-perform-worse-on-edge-and-firefox

Mozilla's Technical Program Manager has suggested that Google’s recent design refresh of YouTube performs worse on Mozilla Firefox and Microsoft Edge, the two biggest competitors to Google’s own Chrome web browser.

The accusation, which was posted on Twitter, suggests that YouTube’s webpages load five times slower in Firefox and Edge compared to Chrome.