Microsoft Store already has browsers like Firefox.
It’s a web app, you don’t really need a native application for it.
Seems like you’re currently using Pop! OS. Just wanted to give you some tips: Don’t install Manjaro, AFAIK their packages are mostly outdated and the distro says it supports the Arch User Repository when it clearly does not and breaks the system. Some more distros that you can use are Nobara (which is Fedora based so there is a chance you will face the same issues), Linux Mint, KDE Neon and Ubuntu.
What does this have anything to do with RCS?
You can use Invidious, Piped.video or FreeTube if you’re on a computer. If you’re on something like a mobile phone use GrayJay or NewPipe. If you want to continue using YouTube normally, Brave’s adblocker blocks those pop-ups completely. Also if you use Ublock try updating the filters.
I started using Piped to get around this. I recommend you do too. Maybe a DNS ad blocker could also work.
If yoı don’t have much Linux experience, probably Ubuntu or Nobara. You don’t need to use the terminal just as much in these distros.
uBlock blocks most trackers already. Also using Fingerprinting protection via another extension or if you’re on Firefox on its settings, they probably won’t get much data on you with ads.
Shut down your phone completely before sleeping. Airplane mode might work also but I’m not really sure.
I use LibreWolf on Debian and just got the update. It doesn’t take that much time.