I set mine even more restrictive, to no notifications at all. Did follow the "learn more" link, which took me to Mozilla's page about Web Push. When I looked at my Firefox notifications settings, there are no websites allowed. According to the instructions, I can block a site, but I think only if it is listed in the first place.
If I'm the only one having this problem, and it isn't an option on the SASS site to turn off, I'll just live with it.
Thanks to you and Sedalia Dave for the help.
EDITED to add screen shot.