10A chargers performing differently

These are both 16s 10a chargers. I noticed that the one on the right(Afu brand) is beginning to charge more slowly than the one on the left (Surron brand). When the pack is at roughly an average of 3.6v my LLT bms always reports a charging amperage around 12a for both chargers, but when they get to an average of 4v/group the Afu charger dropped the amps to 4a. When I swapped the Afu for the Surron charger the charging rate jumped back up over 10A. The surron charger does slow its charging rate but usually not until it’s closer to a 4.1v/group average… It seems like the Afu charger’s performance has dropped off some. Is there something I can do to bring it back up to speed?

Just to confirm…it used to continue the fast charging for longer?

Have you changed anything with its wiring or connector? Are the connector pins clean?

I ask because a higher resistance connection can cause a voltage drop that makes the charger think the charging is nearly done so it drops the charging current (to “top off” the pack) too soon.