It sounds like you may be saying that the act of zipping/extracting is replacing/corrupting the file creation date field from the date the photo was taken to become the date which the photo was zipped/extracted/downloaded.
I believe that this is a symptom of ProtonDrive's photo function not being a true synchronization. Rather, it's more like 'auto-upload.' It's frustrating that Proton is off doing crypto wallets, etc. while they don't complete the building of the products they already have. I use Proton, and I'm rooting for them, but they really need to hire a (new) Product Manager.
As a workaround, perhaps you could download all your photos to an external drive from your iPhone, then load the photos onto your new phone by USB. Then, let the Proton Drive app upload the photos to the cloud. You might want to test this with a few photos first to make sure it actually works.