[peetistaken]

Not really. They can‘t see a list, as navigator.plugins is dummy data in every major browser, but they might able to detect eg. Adblockers by other means

[dubcanada]

Adblocking is not rocket science, you block the DNS of the ads. Some also use JS to mess or remove ads.

All of this is easily detected, can I ping X, can I see DOM Y, etc.