I’m also surprised that people see this kind of ads: I haven’t seen any since I removed Outlook free (after Windows prompted me to switch because the older UWP Mail app was being retired). I’m always surprised when people complain about the number of ads they get in Windows.
But that’s not the point: the point is no paid software should contain any ad.
I checked on my machine, and out of all the packages I had on snap, only Inkscape, VLC and Slack were also available on apt. Spotify, Whatsdesk (a WhatsApp client) and Signal were among the most commonly used missing.