1) Large Caves are being affected by the daylight cycle when RTX is enabled. When time is set to day things in the distance appear to be lit up by the sun. When time is set to night things look as they should. (Clip 1 in the video)

2) This is especially obvious when under water in a cave. When time is set to day everything is super bright underwater and a horizon line is being rendered. Some areas even have godrays from a light source that isn't actually there. At night everything looks as it should. (Clip 2 in the video)

3) I think the cave light bug can be explained by distant parts of the cave not rendering therefore skylight is leaking in through the hole and rtx is bouncing this light off everything. (Clip 3 in the video) This doesn't explain the underwater issues though unless a large chunk of the cave just stops being rendered when you go under water and all that light is coming in. That wouldn't explain the horizon line though.

Some of these issues appear in regular non-rxt vanilla mode as well. You don't have the caves being lit up by bounced light, because there is no bounced light without rtx, and you don't have godrays and horizon line under water. You do however still have distant parts of the caves not being rendered and holes appearing and it does get brighter and darker under water in the caves depending on time of day. Also if you look up under water you do see a lot of areas not rendering and holes appearing.

Video of the RTX bugs: https://youtu.be/VFxro__x3hU