Surprised at this... He was taking his reps with the first team this spring.
The only reason I can think of is that he doesn't like Bryan Harsin (there's quite a long line there) as his OC, and that there are a lot of players who fled Berkeley because of Harsin (namely their entire running back stable).
Link: https://www.si.com/college/cal/football/cal-wr-tobias-merriweather-enters-transfer-portal-01jsyvcw53dm