iOS 17.6.1, Safari with no content blocker, I turned on Lockdown mode and I got <Do you want to download "no_match_opted_out"?> while reading the forum. I wasn't logged in, but I had accepted all cookies. "Prevent Cross-Site Tracking" is off. Download didn’t download anything.
Usually that sort of thing is due to a misconfigured ad. Fortunately, it means they usually go away on their own when the ad goes out of rotation. Are you still seeing it?