Pale Moon is a wonderful web browser. I use it as a daily driver. Some websites think it is outdated and will actually send a page saying, “Your browser is outdated. Please update to a modern browser to use this site.”
I disagree with their assessment. Additionally, Pale Moon has the ability to change the user agent when talking to domains. You can just make a new entry in the about:config page.
|general.useragent.override.deviantart.net||Mozilla/5.0 (X11; Linux x86_64; rv:3.4) Goanna/20170101 PaleMoon/27.6.1|
|general.useragent.override.netflix.com||Mozilla/5.0 (X11; Linux x86_64; rv:45.9) Gecko/20100101 Firefox/45.9|
Just make a new entry with name: general.useragent.override.domain.com. And just experiment with the user agent string to send until you get it right for the site in question.