I just changed my iPhone XR battery and it can’t read my battery capacity yet

The notifications indicate that the iPhone did not receive a genuine Apple battery. The issues will continue if that is the case.

Did you have an Apple Store or authorized Apple Service shop install the battery? A lot of shops claim they can service Apple products, but they are not authorized to purchase genuine Apple parts. That is likely the issue here.

Please provide more details on who installed the battery.

If you changed it yourself or had it done by an unauthorized shop, it will never be able to read the battery health.

You have rendered your phone unsupportable by Apple.