Came here to make the same post. Same issue here, but not sure how long it's been going on (but I think at least a few weeks). Notifications are enabled in the app in general and for my account, and notification permissions for the app are also enabled.
I download from F-Droid and have had other F-Droid apps not do push notifications because they don't ship with Google play services or whatever. Maybe that's related? Or maybe it's a GrapheneOS thing. Neither may apply to you, though.