While I’m not using telegram (and you should neither, it sucks and it’s bad for privacy), here are two options:

Change your DNS. If that’s the way they’re distributing their ads, they’ll be gone

Maybe Telegram FLOSS (F-Droid-Store) can help?

I recently heard that manjaro cinnamon comes with Vivaldi pre-installed

You, my friend, use Linux from Scratch

I think this would be Vanilla OS