It appears the phone's processor is having an issue with the device referred to as the ad5860, which is apparently a chip mounted on the Taptic Engine. Generally the fix for this in at least one other case is to replace the charging port flex cable assembly. See this previous question for more information; it's regarding a XR rather than a XS Max, but the sensors and causes are the same.
[post|713457|SOLVED: iPhone Xr randomly bootloop at random moment - iPhone XR - iFixit|new_window=true]
Alisha (@flannelist), have you run into any new information regarding that particular device in the last three years?
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=== Update ===
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I just noted that iFixit doesn't have a guide for replacing that part, so I went ahead and located one on the Spanish site Nadie Me Llama Gallina. It is, of course, written in Spanish, but if you use it with the Chrome browser, its built in translation feature works quite well with the site.
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[link|https://www.nadiemellamagallina.com/en/manuales/smartphones-1/apple-5/apple-iphone-xs-max-862/flex-con-conector-de-carga-y-micr-fono-inferior-7516|Manuales / Apple iPhone Xs Max / Flex with load connector and lower microphone - Nadie Me Llama Gallina|new_window=true]
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As for the part itself, you can buy that right here on iFixit if you want to support their repair efforts.
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[product|IF407-012|iPhone XS Max Lightning Connector Assembly|new_window=true]
It appears the phone's processor is having an issue with the device referred to as the ad5860, which is apparently a chip mounted on the Taptic Engine. Generally the fix for this in at least one other case is to replace the charging port flex cable assembly. See this previous question for more information; it's regarding a XR rather than a XS Max, but the sensors and causes are the same.
[post|713457|SOLVED: iPhone Xr randomly bootloop at random moment - iPhone XR - iFixit|new_window=true]
Alisha (@flannelist), have you run into any new information regarding that particular device in the last three years?