Here's a GIF:

Forge 14.23.5.2847
astralsorcery-1.12.2-1.10.23
Forgelin-1.8.4
betterportals-0.3.7.7

That likely needs to be fixed in astral sorcery. Their sky rendering code probably assumes there to be only one world loaded on the client at any one time, which is generally true except when BP is installed.

That likely needs to be fixed in astral sorcery. Their sky rendering code probably assumes there to be only one world loaded on the client at any one time, which is generally true except when BP is installed.

Could you... file some kind of issue to them? I'd do that myself, but I'm not knowledgable enough to explain this issue.

Well that was easy

Their sky rendering code probably assumes there to be only one world loaded on the client at any one time, which is generally true except when BP is installed.

Well, rendering a 2nd world will cause the gateway shield - the black sphere shown flickering there - to stop rendering as it's not the world its associated source is in. Next tick the shield-effect gets spawned again since the tileentity is missing its shield-effect. Rince and repeat.

Not fixing this as development focuses on newer versions now.