Makes sense. They must have harvested my getAlby address, so I've been getting the ad messages there. As it's a browser extension, it's less visible than getting popups on your phone with WoS.

As a side note, WoS today has said they won't show notifications anymore for this type of messages, as a response to the amount of spam people have been getting. You still get the sats, but you must actively look for the messages in your history to read the ad.