My wife and I have used Linux, several different distros, since 2007 when we permanently ditched MS. Combined, that's over 30 years of use. My wife, early on, wanted a word game provided by a well known news site as a browser extension. It was nice except for it being a persistent hijacker that stole her browser home page and couldn't be uninstalled. Scared the sheet right out of her - "I thought you couldn't get nasties with Linux." We learned from that. The fix was easy, I purged the browser package, then to be sure there wasn't a stubborn memory element I rebooted and then reinstalled the browser. The extension was gone. Yeah, we learned then that crap can happen on Linux. That was our one and only brush with nasties.
Since then I've used ClamAV. It won't help with conventional adware type malware, but with the urlhaus script addition from https://github.com/abusech/urlhaus/blob/master/clamav.sh I get more AV signatures. We've got a couple added repos beyond the authorized Linux repos, Spotify, Brave and Speedcheck so I run my own custom script to update and scan my system maybe once a month, probably more like every couple months. We don't use a server so the urlhaus script doesn't run as often as urlhaus recommends, just when I run my AV script. Linux keeps a very tight hold on their repo security but I'm not so sure about the three additional and independent ones we use. Now, the only nasties we find are in email attachments that are in our junk folders.
There are now more desktop users of Linux than ever before and I agree, there needs to be some serious attention paid to preventing or eliminating adware and such, specially since most new Linux users are MS users and used to the way MS (mis)manages things. It probably wouldn't be a bad idea to have a live service AV for Linux either if only to check downloads.
I'm lucky that WAY back in the early days of DOS and MS I learned fairly in-depth BATCH file scripting and it wasn't much of a learning curve to switch to BASH. So many say there's a learning curve switching from MS to Linux, but for both of us, it was more like a little slope, even 15 years ago before desktop Linux became well polished. My wife, retired from full time for many years, was a medical secretary for 40+ years.
BTW, we both use Debian and I think that's where we'll stay.