I made a change in my contextual menu management in v9.1c , released on 21 Sep 19. I don’t know if it could be the source of the problem, but I remember vaguely a similar problem back in SU7 and SU8.
So I recommend you migrate to LibFredo6 v9.4b, in which I reverted the change.
Thanks to advise if you see a change in the issue
Note for developers: this relates to the creation of new instances of UI::Command objects in a contextual menu handler. These objects are not fully released at API level and after a while they exhaust the system buffer for menus. I think this only happens of Windows.