FWIW I’ve noticed this on my Pike Ultimate from new. It’s definitely not leaking from the bladder and the damping is working just fine. If I dial in more Rabbits, the clunk goes away but I’ve been experimenting with very fast rebound damping and I’ve left it as it is.
Having said that, it could indeed be the damper if no amount of additional rabbits fixes the clunk.
Pikes are very easy to do a lowers service on. See the SRAM videos on Youtube, you’ll need a 5mm Allen key, a mallet and some fork oil to replace (I think RS specify a particular 0w30 but in reality anything will be OK). If 120ml of fluid comes out of the bottom of the right leg, the bladder has blown. Otherwise it’s OK.
TLDR: Try adding more rebound damping. If that doesn’t fix it, it’s service time.