photos taking up lots of space after new phone transfer

Got a new iPhone Promax (256gb) and decided to transfer back up from my Promax 11 instead of doing iCloud backup. It all works great, apart from one thing that puzzles me a bit. I use iCloud photos to manage my photo library, I have over 30,000 stored there. On my old phone photo storage was taking up 14GB. However, after the transfer, I find out my photo storage is a massive 129GB! So obviously during the transfer, a huge proportion of my iCloud photos was downloaded at full resolution. As iCloud manages the storage I assume there is nothing I can do, just wait for it to gradually replace the full resolution photos with smaller device sized versions as it’s supposed to do.