Is 60W charging normal for an 87W USB-C Power Adapter?

The power adapter I have been using suddenly dropped from charging at 87W to 60W. When I look in the "System Information" i see this:

Connected: Yes

  Wattage (W): 60

  Name: 87W USB-C Power Adapter

  Manufacturer: Apple Inc.

  Hardware Version: 1,0

  Firmware Version: 1070069

  Charging: Yes

Sometimes plugging it in and out of the power outlet fixes this issue, and it starts charging at 85W again, but this stopped working recently.

Is it a battery protection measure or age issue with the adapter itself?

[Re-Titled by Moderator]