Transfer from one phone to another iOS

Issue re phone transfer.

Brief summary and questions (submitted to AB2 support). Any thoughts or help?

– I bought an iPhone 17 and transferred data, etc., from my old iPhone

11 to the new phone. Most everything transferred fine except for AB2.
– On the new phone, I keep receiving an error message (Oh, no something
went wrong with a string of numbers as the error code).
– The game still works on the old phone, though that will have to be
traded in soon. I am using the support chat on the old phone, but so far no
resolution. Support has indicated they have made adjustments in my account
several times but nothing has helped so far.
– I used to believe when I used cloud backup in the game that it was
going to your servers but I read that that is no longer the case, so I
“signed in” on the old phone to my iCloud account and did a back-up there.
The cloud icon now shows a green check-mark when I do that.
– If this cannot be fixed, can I delete the game on the new phone
(without affecting the data supposedly uploaded to iCloud from the game on
the old phone), re-download the game to the new phone and hope that it will
pick up my data correctly?
– If I do that, do I need to turn on or off syncing, so that deleting
the game on the new phone does not affect data stored in iCloud?
– Also, if that would work, would deleting the game from the new phone
affect the gaem on the old one, too? Or would that stay as is?
– As noted, the old phone still works okay but I don’t know how long I
can keep it and it’s my only method of contacting support via the game at
this point and the only way I can continue to play the game (uploading
progress after each play).
– I have played this game for years and do not wish to lose all this
progress.