Lol, well don’t jump down my throat about it sheesh. Not everyone’s going to have the same hardware as you. You had provided zero information about what extensions you’re running and you didn’t even provide a link to the site for testing. I had to google it to find out which page it was. With that lack of info, all I can do is test on my end and see if it was also happening to me to find out if it was a general issue or hardware specific.
I’m sure this is webrender problem
If this was a Webrender problem, I would also see it on my end. It’s more likely that its a GPU driver issue, especially since you’re using a phone that has an old version of Android that’s no longer getting any updates.
Also, you aren’t going to get much help here beyond the usual “it works for me, it doesn’t work for me” for these kinds of issues to be honest. This isn’t a place developers frequent. You can find better help if you submit a proper bug report here: bugzilla.mozilla.org