Falling through the ground and into the void when entering a portal to the other end islands

So when i threw an ender pearl into the one of end island portals, fell straight through the portal and the ground beneath to my death, i lost all my mending gear because of this btw, and just to check if it was just happening with i tried on the 3 that we had opened and it happen with all three.

Edit: I've now found that when i throw an ender pearl at a block above me, if there is space, i teleport through the block, so maybe that was the bug and not anything to do with end the end portal. I'm so confused help.