Apple ISO 12.5.7 no longer working

I’ve discovered to my cost and without notice that ISO 12.5.7 is no longer compatible with the GivEnergy App. I have a cheap and cheerful iPad mini on the wall in the kitchen giving a constant display of the inverter/battery/solar panels status but in the last few days the app shuts down after 45 sec. I would really like to know from GivEnergy what versions of Apple ISO are compatible. Would anyone like to buy an Apple iPad Mini 2 Wi-Fi 16 GB for just a few pounds?

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Same here on iPad Air running sw version 12.5.7. Can’t upgrade to iOS 17-too old!

Same here... older ipad now useless with the app.
No warning prior to updating the app either.