Brand new Bluto fork that came as 80mm standard, I switched out the air shaft for a 90mm version and lubed up liberally with slick honey.
I noticed what at first felt like a small knocking when travelling along flat ground but couldn’t detect any looseness anywhere on inspection.
Today I noticed that when pressing down on bars the travel blows through about 2-3mm with very little resistance before instantly ramping up. I run the air pressure pretty high and have 4 bottomless tokens fitted.

Any ideas?

It doesn’t feel critical, but is noticeable enough that it’ll annoy the hell out of me from now on.
Could it be some form of new fork stiction?

My solo air rebas do this, and my revelations (dual air I think) both a few years old and not recently serviced, but I think it’s just a quirk of them. The revelations are on my zesty, which I’m more wary about knocks and rattles on, being my first full sus, I have thought the stem or headset was loose more than once but eventually worked out it was the forks, as you describe.

I always found solo air needed to be run at lower than recommended pressures to get the best out of them. Presumably you’ve tinkered with this, and the number of tokens?

Alot of forks and shocks will yield a mm or 2 with no resistance as its the seals moving around, that siad Ive not noticed it on RS forks. Might be worth checking your seals are fully seated on the air shaft.