If the alternator is charging the battery properly and the battery is good. Then the only explanation is that there is excessive parasitic draw (current drain) on the battery.
All electrical circuits will have some amount of draw, however when it becomes excessive it will drain the battery fast, many times it will drain it completely overnight.
This vehicle should have about 25 milliamps of parasitic draw, which is considered normal.
To determine what is causing the draw you will need to use a multimeter and check for the draw at the battery while removing different fuses for different components.
Here is a helpful video showing what to do:
Please let me know if you have any questions.
Images (Click to enlarge)
Tuesday, January 11th, 2022 AT 9:48 PM