I have an iPad Pro 2020 11-inch which currently runs the latest ipadOS 15.2
I have found this link:
https://dhinakg.github.io/delayed-otas.html
If I understand correctly they mention that I can do a delayed downgrade to 14.8.1. Is this true? How can I do that?
To give you a direct answer first, you cannot downgrade from a higher version to a lower one with this method, you can only upgrade to a higher one if the profile is still valid. At your present situation, you can only go to a higher version.
Now, even I have a crude understanding of these methods as I have been out of jailbreaking from quite sometime so take everything I say with a grain of salt and do read on reddit jailbreak forum for a detailed understanding of these things.
There are presently two methods of upgrading and one of downgrading to an unsigned firmware.
First one is the method you listed here with
delayed OTA update. This has an expiration date as mentioned on the website. These profiles are intended for organisations that let them update to an unsigned firmware for a specific period of time. You cannot downgrade with this method.
Second method is with blobs which allows you to upgrade and downgrade even if the firmware isn't signed by apple.
You need blob files for this method. Every firmware has specific blob files which one can save for a specific device when the firmware is still in signing by the apple. For example you can save the blob files for 15.3.1 right now for your device as it's signed by apple right now.
Now there are a few ups and downs for this method.
You can in theory downgrade from a higher version to a lower one and vice-versa with blobs if certain criteria is met. One of these conditions is the SEP file compatibility. There's a SEP file associated with each firmware which you have no control over and apple updates it (or not) with each firmware. So, if there is a SEP file mismatch you could lose Face ID or Touch ID if you attempt downgrading. You cannot save blob files if apple has stopped the signing of the firmware.
Generally speaking, there's mostly always a SEP change when the jump between the versions is higher like iOS 14 -> iOS 15 though there could be exceptions.
I think you also have to be on a jailbreak-able firmware as there are other steps involved in it. You have to read on it on the reddit jailbreak forums for detailed info.
This method is very risky in my opinion if you're unfamiliar with it. Everything could go wrong and all hell could break loose if you don't know what you're doing.
If you don't have blob files saved then you might as well just skip all this as you won't be able to downgrade.
