Will deactivating "Find My" erase all my data in the iPhone?

I was in Apple Store to change my water damaged iphone 13 mini with new one, however the employee in Apple store had adviced me to unlink my İphone without erasing the content and I had concrerns about my data privacy.The screen was damaged, with the current screen it is not possible to open the Iphone, however I was in an external repair store where I could open the iphone with External display where I could see all my data.So the memory is not damaged and all my infos are inside there.I have concerns about my data privacy.And I also suggested why do we not erase the content before deactivate the "find my " for this iphone but he insisted on that was the right way.