Battery charging issue

Okay, I do not think your problem is related to your battery (unless it is faulty).

Read section "If your device stopped charging at 80 percent" in the support article I posted.

Take also a look at this useful user tip:--> When to charge your iPhone or iPad - Apple Community

Regards

Giulio

With iOS 13 and later, Optimised Battery Charging is designed to reduce the wear on your battery and improve its lifespan by reducing the time your iPhone spends fully charged. When the feature is enabled, your iPhone will delay charging past 80% in certain situations.

About Optimised Battery Charging on your iPhone – Apple ...

Is that an old SE or is it an SE 2020 model?

Start here for help:-->If your iPhone, iPad, or iPod touch won't charge - Apple Support

Regards

Giulio

Turn off Optimize Charging. It keeps the device to 80% charge.