Just thought I’d chime in on this, as I’m a relatively new HubSpot user, and I’m pretty sure I was in exactly the same boat, and have found the solution.
I regularly provide software demos and notifications about other customers were appearing during demos.
At some point, I appear to have installed the HubSpot for Windows app. I’d tried pausing notifications in this (in system tray > right click > pause notifications), and was wondering why I was still getting notifications during demos.
The above solution has worked for me, but perhaps other affected users are in the reverse situation (i.e. have disabled desktop notifications through HubSpot, but still have the HubSpot for Windows app active).
My recommendation, if you’re having this issue, is to ensure that you check that you’ve checked both in HubSpot > Notifications, and also ensure you’ve turned off/uninstalled/paused notifications in the HubSpot for Windows app.
Hope this helps!