Hi Bogdan,
I have a different expectation. While Bookmarks save the Focus tool and are ordinarily dynamic, as you have noted the “3 month” reference gets changed to a specific date. Bookmarks I have made with that filter continue to display albums added from the specific date rather than dynamically adjusting to a new date. It’s not a huge hassle because you can easily create a new last 3 months filter, but I would prefer Roon to have a dynamic last 3 months filter.