Try setting DRI_PRIME=0 in your environment. There are logs in ~/.local/share/dV/ directory, you might take a look there if something seems off.
This DRI_PRIME=0 will start the game no the same intel GPU (which is stable, but sloooow).
Godot Engine v3.4.2.stable.official.45eaa2daf - https://godotengine.org
OpenGL ES 3.0 Renderer: Mesa Intel(R) HD Graphics 5500 (BDW GT2)
OpenGL ES Batching: ON
On DRI_PRIME=1 it tries to find nouveau and then runs on Intel:
Godot Engine v3.4.2.stable.official.45eaa2daf - https://godotengine.orgAnd here how prime-run starts games:
libGL error: failed to create dri screen
libGL error: failed to load driver: nouveau
OpenGL ES 3.0 Renderer: Mesa Intel(R) HD Graphics 5500 (BDW GT2)
__NV_PRIME_RENDER_OFFLOAD=1 __VK_LAYER_NV_optimus=NVIDIA_only __GLX_VENDOR_LIBRARY_NAME=nvidia "$@"