Half the time I hit the Tinkercad user home page there is a banner announcement at the top. These banners take up space on a page that already makes inefficient use of prime real estate at the top. Sure, I can close the banner ads. But it just reappears again next time I open that page.
I'D suggest that each dismissed banner stay dismissed on subsequent visits. I'd prefer that there be a preference that allowed users to opt-out of all announcement banners. But short of that,it should be sufficient for a user to dismiss a particular ad once and know that they won't be exposed to it again.