WhatsApp messages older than 4 years are gone

This week I found that messages from before 2021 disappeared from my WhatsApp chats. I realised because I was searching a chat for a recipe that a friend sent me once. I‘ve used it regularly, but this time it was gone. I scrolled up a couple of other chats and saw they all stop some time in 2021.

I googled, but could not find any information about any such kind of limit. Does anyone have a clue?

My phone has 256GB memory, I have a limit of 200GB on iCloud, and my WhatsApp backup size is about 9GB. I switched to a new iPhone a couple of weeks ago, maybe it happened when transferring the data to the new phone.