Samsung Galaxy J5 / J500 Charging Issue: Slow Charging Rate and Inconsistent Battery Percentage

It only started about 3 days ago. Terribly slow charging but standard discharge time. I discharged the phone and charged it again. 40% charged in 3h ... I checked on other chargers - the same problem.
With one charger and the other with a removable cable, the charging current varies from -3mA to 280mA, with one of the cables it is from 250mA to 550mA (with it it shows that 1.5h remains to be fully charged, and must recharge about 40% more).
Plus, when turning off the phone (47%) and rubbing those golden plaques from the battery, it was magically 56% after turning on.

Hello

The battery is used up. It will not charge as fast as it used to because the voltage on the cells jumps, which is confusing for a charger that charges with a lower current. I have a Samsung Galaxy Tab 3 for about 6 years and have never replaced the battery. the tablet is charged about 10h, the battery lasts about 2h (used to be 2/6). I bought a new cable and it didn't help. However, when I used the huawei charger cable, I significantly reduced this time by about 4 hours.