Faint battery light

2007 Toyota Yaris, 90,000 original miles. Replaced the alternator due to the battery light being on. The battery light is on, but not solid, just a faint outline of the light. All connections are reading the proper voltage, except for the L wire, which reads 10.5v.

My OBDII reader shows a low-voltage incident, which is understandable because I replaced the battery after replacing the alternator.

No stored codes.

The battery voltage is 14.5 at idle.

Bad voltage regulator in a supposed new alternator that I got from Parts Geek?