Thanks for flagging this. We're looking into it from our side.
In the meantime, please don't click on the antivirus warning or download anything it suggests – just close the pop-up or browser window. Seeing one of these warnings doesn't necessarily mean there's anything wrong with your device.
Unfortunately, rogue ads can occasionally make it through the security filters used by advertising networks. They're deliberately designed to evade detection and can sometimes behave differently depending on the device or browser they're being shown on, which can make them tricky to track down.
If you can, please send us a screenshot along with the device and browser you're using and roughly what time you saw it. That information is really useful in helping us identify and block the culprit.