Quick answer: Godot 4 _physics_process receiving delta > 1/60 when window backgrounds? Engine.physics_ticks_per_second is fixed but the engine catches up via repeated calls - clamp velocity or use a fixed sub-step.
Player walks 10 meters in one frame after un-minimizing the game. The single catch-up tick uses an accumulated delta.
Cap max physics steps
Engine.max_physics_steps_per_frame = 8Limits catch-up to 8 ticks max per frame. Anything beyond is dropped - players miss simulation time but don't teleport through walls.
Use fixed delta for motion
In _physics_process(delta), ignore delta and use 1.0 / Engine.physics_ticks_per_second. Delta only reflects accumulator state; the real per-tick step is fixed.
Pause on focus loss
Listen for NOTIFICATION_APPLICATION_PAUSED and set get_tree().paused = true. Eliminates accumulator drift entirely.
“Physics process is fixed-rate. Delta is a hint, not a contract.”
For competitive multiplayer, both peers must use the same per-tick delta. Accept the desync risk and bound it explicitly.