External website will stop support for browser
The official dutch website: https://www.uwv.nl/particulieren/ shows the message: Deze verouderde browser wordt (binnenkort) niet meer ondersteund! So it says that Firefox is too old as a browser to be supported by them (I have the latest version of Firefox 86.0.1). Does that mean that I cannot use Firefox anymore to visit that website? I don't know if there is something Firefox can do, or if this official dutch website is wrong in supposing that Firefox will not work anymore.
Alle svar (3)
Their script is written to give this message for any version of Firefox, any version of Opera, any version of Internet Explorer, versions of Chrome before 86, versions of Edge before 87, versions of Safari (or mobile Safari) before 14, and versions of Samsung Internet before 13. I don't know the logic behind this selection of browsers.
Note for any tech evangelists: see https://www.uwv.nl/particulieren/include/js/scripts.b5271c0.js
Their browser detecting code is very strange; when comes to Firefox they even don't check the version. So they don't know if it's too old or not. The message is shown in every version of Firefox.
I don't know if it's by design, but for me it looks like a mistake.
I would suggest to contact the website about this issue with Firefox. You can usually ignore such a message if you use the current release and proceed.