13? I'm still happy with my 12 mini!
As long as the battery continues to hang in there, I haven't seen a lot of reason to upgrade.
Is it not possible to replace the battery on a 12 mini?
EDIT, apparently it is:

iPhone 12 mini Battery: Replacement Part / Repair Kit
Replace a 8.57 Wh battery compatible with iPhone 12 mini. 3.85 Volts (V).
