Firefox is gasping for air. So slow and sluggish, especially with many tabs. Hence why they lost millions of users in the last 5-10 years. They tried to re-invent the browser multiple times, and failed. Still slow.
Firefox went from like 20-25% marketshare 10 years ago, to ~5% today.
Most sites are optimized for Blink these days, which powers Chromium and all browsers based on Chromium. Probably has 80-90% marketshare. Chrome, Edge, Brave, Vivaldi, Opera, Arc, DDG and many many more, all based on Chromium.
So yeah, kinda lost hope in Firefox and stopped using it myself years ago. Still have it installed, when I want to check progress, still slow.
Gecko and WebKit have little future is my prediction (Firefox + forks and Safari) most web devs optimize and test in Blink.
Chromium based browsers also gets speed advantage in Windows 10/11 due to Edge being Chromium. Nothing new. Firefox is working against the grain.