Same issue last couple of days. Repeated full page ads jumping across my screen. Very annoying.
ad pop up on chess board during play

I had this issue, too. I was using Chrome when it happened. I switched to Edge and haven't had the issue. So, either they fixed the issue or Edge does a better job of blocking pop-ups.
ETA: Actually, I'm browsing the forums in Chrome and Chrome is still blocking pop-ups. IDK if the site owners intend to serve pop-up ads.
No, pop ups are not intended

Obviously they are trying to get more ad revenue.
If it was malware it would happen on other sites but it only happens here.
the malware could only target cc

The problem is bad ads, not something the site is doing. Staff have worked on disabling ads that seem to be causing the issue and are working with the ad providers to get them removed from their systems as well and not make them available for the site. Most of them should be stopped now as I understand it.
If you still see some can you gather the information from this and report what you're seeing?
https://support.chess.com/en/articles/8647548-how-do-i-report-a-bad-ad
I had this issue, too. I was using Chrome when it happened. I switched to Edge and haven't had the issue. So, either they fixed the issue or Edge does a better job of blocking pop-ups.
ETA: Actually, I'm browsing the forums in Chrome and Chrome is still blocking pop-ups. IDK if the site owners intend to serve pop-up ads.