Willis reverted to the 49ers' practice squad Monday, per the NFL's official transaction log.
Willis was elevated to the active roster ahead of Sunday night's 42-38 win over the Bears. The tight end helped fill in for George Kittle (ankle), but he logged just one snap on offense, far behind Jake Tonges (50) and Luke Farrell (27) in offensive snaps. Willis was able to secure one tackle while playing 24 snaps with the special-teams unit. If Kittle remains sidelined Saturday against the Seahawks, Willis could be elevated again for the team's final regular-season contest.