I'd start with the easiest things first. Make sure the headset is tensioned and tightened correctly and that all the levers on the bars are tight and not rattling. Sometimes stuff on the bars or fork like brake cables can sound like the fork/shock. If that is not it ...
The right hand side has the dampening valve system on the Revelation. Could be any of the internal parts. How many hours do you have on the shock? The 200 hour service on this shock would replace or adjust most if not all of the internal wear parts that could be causing this noise. You can verify the rebuild kit that you need with RockShox/Sram with a phone call and provide them the Serial Number from your shock located on the bridge. In my case the rebuild kit number was 00.4315.032.642 and about 35 dollars. You can find the manual to do the rebuild online.
You will need some allen wrenches and some Fork Oil, Slickoleum type grease, and a short section 1-1/2 ABS sewer pipe to do the rebuild. It takes a couple of hours for me and the shock is butter smooth and quiet when it is done.
I know this might be a long shot but just had a clicking on my 2019 Levi and it was the chain guard by the pedals that had moved up and was hitting the chan moved it down slightly an it went away.
Hi, Thanks for the replies, was passing local bike shop and they said to pop it in, turned out to be the rod coming from the dampening adjuster had become miss-aligned, so full fork service and fixed the problem £90...