No, Patrick Mahomes didn't get injured against the Seahawks. Based on the wiki, Mahomes tore his ACL and LCL during the 2025 season (Week 15), and that injury is the one he's been rehabbing through 2026 — not a Seahawks game. The Chiefs and Seahawks didn't have any reported incident involving Mahomes getting hurt in their matchup.
(from the Patrick Mahomes II page)