①, on the above why the charging is fast before, and now it is very slow, mainly check whether the original charger is normal (if necessary, it should consider replacing the test).
(2) Check whether there are problems such as poor contact inside the original charging data cable (if necessary, you should consider replacing the test).
Check whether the battery inside the phone is normal.
After passing the above check, under normal circumstances, or slow charging problem, it may be a system software problem, or related to the charging circuit, USB interface accessory circuit. For reference only!