It doesn't take a genius to realise this. The tempo of attacks during last winter was what it was and now almost suddenly they barely launch a handful a week in comparison.
Knowing roughly what their monthly production volumes are of ~50 per month across their various systems as of last winter, they haven't been expending anywhere near that amount. The missiles have to be going somewhere, and it's obviously into stockpile. https://jamestown.org/program/russias-estimated-storage-of-cruise-missiles-may-2023/
It is absolutely imperative that we get as many of the needed AD systems into Ukrainian hands ASAP in preparation for this coming onslaught. Another consideration that isn't being discussed is that we should have been stockpiling spare parts and supporting infrastructure for their utility infrastructure (transformers, generators, tents and such) so that they're able to quickly make required repairs and provide shelter to those that need it in the event of inevitable successful strikes.