Have you had a new battery installed by an unauthorised repairer? If so, your iPhone is detecting that. Here is a link that should help you find an authorised repairer:
iPhone Repair and Service – Apple Support (UK)
Apple Intelligence is now available on iPhone, iPad, and Mac!
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Either you had your battery replaced with a non-Apple battery or there's something wrong with it. The only way to resolve this is by having Apple replace the battery with a genuine one:
battery healt
battery healt