v69 breaks OpenXR cubemaps with compressed textures

Our application creates a XR cubemap layer and applies textures to it.

The cubemap layer is the usual type XR_TYPE_COMPOSITION_LAYER_CUBE_KHR.

The 6 textures are loaded from KTX files and use the GL_COMPRESSED_SRGB8_ETC2 format.

Starting with v69, this method for creating the environment around the user stopped working and our UI elements just float inside a black empty space.

This functionality broke also on our *published* version of the application, so it was probably not caused by a bug on our end. Everything worked fine on v68 and it broke on v69,

We have been investigating this issue for several days and it seems that the problem is specifically triggered by the combination of compressed textures and a cubemap layer.

Some additional observations:

• Textures with format GL_COMPRESSED_SRGB8_ETC2 or GL_COMPRESSED_RGB8_ETC2 do not work.
• Using PNG files for the cubemap does work (GL_RGBA8).
• Disabling layers also works.
• Loading other textures with the same formats works (we do it for the controllers).