The landing page scrolls with 2 fps on my phone, making it completely unusable.

I wish there was a browser setting to disable CPU-heavy CSS filters in Firefox to fix pages like this one.

I couldn't believe this but I see other threads on the Internet from over a year ago complaining that Firefox can't handle the backdrop blur filter performantly at all. Chrome has no issue; I had to squint to even figure out what heavy work might have been weighing Firefox down. This design element has been everywhere for years, I didn't know it had gotten this bad at Mozilla.

What is your mobile phone and browser?

Don’t use Firefox. It’s practically no longer a maintained browser engine because Mozilla has other priorities. Not a problem in Safari or Chromium.