Help request: can’t remove factory rear differential breather valve

So I bought an ARB rear diff breather and was going to do the upgrade. Step 1- remove old breather valve... fail. The existing valve just spins in place (not the copper cap, the actual hex-head itself).
It just spins and spins, suggesting to me it is internally stripped somehow. Not sure if I should just give up and return the kit or if anyone has any ideas.

 

Wedge a flat blade screwdriver tip, or other metal spatula between valve and diff, and apply upward pressure, with a twist motion, while turning wrench.

 

I wouldn't take it off just yet, read this, trying to figure out if the new one will go in.

https://www.tacomaworld.com/threads/might-be-stuck-midway-through-diff-breather-mod.633382/

 

My 2021 rear axel breather is a 1/8” pipe thread. Had mine out the other day to see what I was going to need to extend mine. Post #2 seems reasonable.

 

Mine was bottomed out like that when I removed it. Luckily no issues but tight as hell. I am not a plumber but I'm pretty sure they advise against bottoming out pipe thread so whoever installs it at the factory gives it all the beans.

As said above, wedge a screwdriver or something that will hold pressure against one side as you try to unscrew. The threads in the axle are fine; threads on the oem breather are probably not existent. If you need more surface to pull or pry on, disassemble the whole thing and go from there. Here's what the jiggly bits inside look like.