Please forward this to Qouteall if possible.

In the "Immersive Portals" mod, jumping into a Immersive nether portal at a certain angle will cause you to phase through the portal without going in it.

^{This situation is almost impossible to avoid.}

This is NOT a suggestion.

FYI, this did NOT take place in 1.21.1.

1.21.1 is the closest version to 1.20.4 I can find.