Lighting is turned off on random frames

Unity 2020.3.19f1
iPhone 12 mini
URP

Does anyone have an idea what would cause realtime lighting to be turned off randomly on one frame? The following images are a sequence of 3 frames captured from the device using Quicktime but the problem happens when not connected to the Mac too. It also happens constantly when playing, one frame in maybe every 15-20 has dropped lighting.

As you can see, the middle frame has no shadows.