WOT on Prime Episode 8 - SPOILERS

[Thalia]

That's a good catch.

But I think Moiraine channeling open the gate is entirely a retcon to explain why they can't just open the gate again for Mat, and to reasonably explain why the rest of the EF5 has to leave him behind. I don't think they intended the leaf to be missing (though they may well have that as part of their explanation).

I rewatched that ep to see if you could tell exactly where the edits were. The footage of the group behind Moiraine when she channels isn't even moving footage, it's a still (their clothes aren't even moving in the wind). I strongly suspect they filmed it opening with the leaf in the first instance and had to change it when Harris didn't return. When Moiraine strides up to the gate it even looks like she holds something up in her hand to me.

We never see Fain with the leaf in the show, there is just an image in the BTS stuff. I think the scene where Loial was in the WT was originally longer and explained more about the ways and how they were opened, but they cut it when they had to change how the gate was opened in that ep. Same reason they cut Fain and the leaf. No point confusing things for the viewer at this point. We'll likely get the avendesora and some kind of explanation later when they travel the ways again.