Create a nether portal facing East/West. In creative mode, glide through using elytra (so that the character model is prone). Normally, traveling into the Nether causes the X and Z coordinates to be reduced to 1/8; however, in this scenario, the coordinates in the Nether remain the same as the coordinates of the Overworld portal. This can also be done in the Nether, in which case the 8x multiplier will not be applied on the way into the Overworld.

This can be used to very quickly bunny hop out to worldbreaking coordinates (as each pass in and out of the Nether can apply an 8x multiplier by only using this bug one way).

The orientation of the portal appears to matter. I was not able to recreate this bug with a north/south facing portal. I did not check whether other methods of making the player prone while entering a nether portal could produce this bug.

I verified this bug by creating a new world and reproducing the necessary steps.