I couldn't find any record of that in the wiki. The 49ers' preseason injury wave this August hit Ricky Pearsall (WR, season-ending PCL), Jordan James (RB, rib fracture), and De'Zhaun Stribling (WR, hamstring) — no quarterback (from the 49ers page). Brock Purdy's only noted injury is the turf toe from 2025, and the most dramatic health story around the team is coach Kyle Shanahan's car accident injuries.
If you're thinking of a QB being hospitalized after a preseason hit, it may be from another team — or a season before 2026, which is outside the wiki's scope. Happy to check a different player if you have a name in mind.