Recommendations or hint welcome

Hints welcome

You could disconnect 1 battery cable, place a bulb/socket between the connection, it will be lit if you have a draw/drain, you could then remove fuses 1 by 1, may need to remove all to be sure, Identify where they go back, maybe disconnect alternator, regulator, to see if they are the culprit.
A DC Amprobe is nice for this as it shows any charge or draw at 1 time.
You either have a bad battery, alternator not charging, or a drain?

. Remove and fully charge the battery. Most auto parts stores will do this for free. Ensure the battery is good or get it replaced.

. Check the regulated battery voltage, while the engine is idling. It should be 14 to 15 volts. If it's low, replace the voltage regulator/brush holder assembly. On older F-150s, access is on the back of the alternator. Remove the four Torx 20 mounting screws and remove the regulator/brush holder. Use a small drill bit or paper clip to retain the brushes, until the new regulator/brush holder is installed. Disconnect the negative battery cable, prior to working on the alternator.

How old is the battery? If it's more than 3 years old you probably need to replace it.