There was a change in version 3.7.3 that made it so the randomly generated End Gateways far out in the End dimension no longer lead to X:100, Y:50, Z:0. In vanilla the obsidian platform would be there, but Better Portals removes that. I assume those gateways now target X:0, Z:0, and likely at the same height as the End dimension's one way entrance portal?

Anyways, if the Cubic Chunks mod is used, this change does not seem to carry over and those End Gateways still target X:100 Z:0.

For reference:
BP's mixin: https://github.com/Johni0702/BetterPortals/blob/398e594e6e3bad62d52a91fd838e676dd4971f64/src/portal/java/de/johni0702/minecraft/betterportals/impl/mixin/MixinTileEntityEndGateway.java
CC's mixin: https://github.com/OpenCubicChunks/CubicChunks/blob/8c07f301d93c064feb8d76856ba30bc38269f17a/src/main/java/io/github/opencubicchunks/cubicchunks/core/asm/mixin/fixes/common/MixinTileEntityEndGateway.java

Not entirely sure why it'd behave like that though.

Cannot reproduce using CC 1028 and BP 0.3.7.4.

Used the gateway near 10168/62/9814 (Seed: -1725803830919381152) and ended up as expected at 10.5/66.5/0.5.