I've been using favorite characters for a long time, benefitting from being able to direct the extra shards I get with covers to my choices. Lately, however, despite my still having favorite characters, I'm getting shards for random non-favorited characters. New bug?
Are you sure you didn’t accidentally favorite multiple characters without realizing it?
I’ve done this many many (many) times myself. You can favorite anyone in the roster screen, and it definitely means you also can favor chars while casually scrolling through your roster……
Is your favourite an ascended character? Your ascended 4* is still going to get 4* shards and not 5*