Device tree and encryption are not the same between android major version
When you come from the last available stock gogol/fairphoneOS, you’ve got latest firmware and stock device tree,
But when comes from an old android 9 based firmware and device tree even with /e/OS pie flavour on it your device is not ready to receive an /e/OS Snow cone flavoured based on latest firmware available and android 12 device tree
So if I’m going to flash the stable Android 11 version of /e/ I’ll get the latest stock firmware and device tree but when I’m flashing the Android 12 version of /e/ that’s not the case?
Judging from experience, it shouldn’t be necessary to install the stock OS on Fairphone 3/3+. The e foundation gets the Fairphone firmware components to include in /e/OS directly from Fairphone via their official partnership.
/e/OS documentation in general is based on templates. When adapting the template default content to peculiarities of particular devices, deleting some unnecessary stuff can get forgotten.
Oh boy, so to sum it up: Some contradicting information on what to do with which device.
Relying on templates is generally a good thing, but when there are dedicated device maintainers, maybe they should also put some effort into documentation.
Reading installation notes should not result in inconclusive information. I hope this will improve in the future Well, everybody keeps learning I guess.