Are Viruses a Concern on Linux After Visiting Risky Websites?

I highly doubt you have a virus on your computer. If it eases your mind, you can run a scan using ClamAV and freshclam to check for any potential issues.

Web browser actions are sandboxed, which means they can't escape the browser environment unless there's a serious security flaw. To prevent unwanted pop-ups and ads, adding an ad blocker like uBlock Origin via the Extensions menu in Firefox is a smart move. You might also check out the NoScript extension for additional control.

It's really unlikely that you've got malware. A lot of wallpaper and image sites have ads that aggressively redirect to random domains. What you experienced is usually just a redirect from a site or an ad script, not something that would infect your system. Since you're using Linux, those web redirects won’t infect you unless you downloaded and ran something harmful. To be safe, just make sure your system and Firefox are up to date, and consider using uBlock Origin to block those ads before they load. It’s a great way to enhance your browsing security!