Image Description:
Taken in Crystal Palace map with It's resource pack.
Normal glass & Normal glass pane, as you can see in the screenshot, everything is Black through Glass block underwater, while glass pane makes water Invisible.

Steps to Re-produce:
1. Download Crystal Palace Map from Marketplace.
2. Enter world
3. Enter Creative mode & give yourself glass & glass pane
4. Place them underwater
5. Look through glass, and glass pane.

I also do Confirm It happens in None-marketplace worlds with custom community resource packs which almost all of them have this set of texture which I attached (glass texture set.zip (in this case they were picked from https://mcpedl.com/truly-vanilla-rtx, I also do confirm it doesn't happen when you apply a normal or mer map, so It sure is Minecraft RTX bug, (and it also happens with several other resource packs i've tried such as defined pbr on mcpedl).

The effect Glass Pane makes is very similar to Structure void block:

Just like glass pane, an Air block underwater makes water invisible if It's seen through it.