As 2019.3 is an ALPHA release of Unity, you might also ask in the Unity forums. I'm not trying to sound snarky, but my first guess is that this isn't an Oculus thing.
What i mean is the actual texture import settings. Make sure you have proper android compression settings applied and that the lightmap size(mb) doesnt push over your ram limit. Use the ovr metrics tool while running on the device to get a proper readout of how much memory you have left.