I looked on Newegg,Amazon US and a few UK retailers. The only RKL SKU which might be a bit hit and miss appears to be the Core i9 11900 series,but the Core i7 and Core i5 series seem OK.Again we will have to only ascertain if availability is truely poor when CNL stocks and production are rundown in favour of RKL. There is that to consider - Intel needs to sell the current CNL stock unless they want to suffer excessive inventory.
You could be right but if they are having issues then it will known by June/July. You saw that with Zen3,when it was quite clear it was either yields or lack of TSMC capacity being available. Even the Ryzen 9 CPUs have been rare as hen's teeth too,although stock does seem to be getting better now. So it seems to be the battle of the CPUs which are hard to get.
However,
WRT to the Core i9 CPUs,yields are not the issue here at least with this one model. It will be the Core i7 and Core i5 models availability being lower which is an indication.The Core i9 and Core i7 CPUs this generation are only differentiated by clockspeed. Yet look at their cost and power consumption. This tells me the Core i9 CPUs are essentially a RKL Extreme Edition,ie,binned leaky parts which can clock higher,and have all the boosting tech enabled on them. They are a marketing exercise and why they cost so much.