Minecraft 20w18a
Fabric 0.8.2 build 194
FabricAPI 0.10.1 build 336
Immersive Portals 0.9

It's also happen in creative, and in singleplayer.
Also I cannot interact with fire which is on the mirror.

You should provide an image or gif in the issue itself for convenience

All my gif are higher than 10MB how can i do ?

Edit : I did it