From VG247: “Apex Legends patch 1.1.1 brought some big changes to Gibraltar, and Caustic but not everything was seemingly mentioned in the patch notes.
The update added a passive damage reduction to both heroes to compensate for their larger size. Gibraltars Gun Shield in particular now absorbs more damage before being destroyed, which is another way of boosting his survivability.”
Source: N4G PC Apex Legends players discover hidden buff for Gibraltar, Respawn investigating