What is Standby Battery Threshold?

Hello,

I have a Macbook air (2019) and truthfully I don't use it very much. When in school I had a Macbook Pro (2009) and the battery life on that unit seemed soo much better. It would last with the shell closed for soo much longer than my current Macbook

Now it seems if I dont use it for a stretch of 10 days or so the battery is completely dead and I need to charge it for a few mins before even being able to use it.

Im wondering if there is something wrong with these settings that might be causing me some grief?

I started looking through my power settings and hard ware report. Here is the data as my battery is showing 29% charge after being completely dead:

Battery Information:

 Model Information:

 Serial Number: F5D91812XLLJ6W6A9

 Manufacturer: DSY

 Device Name: bq20z451

 Pack Lot Code: 0

 PCB Lot Code: 0

 Firmware Version: 1002

 Hardware Revision: 1

 Cell Revision: 1838

 Charge Information:

 Charge Remaining (mAh): 1085

 Fully Charged: No

 Charging: Yes

 Full Charge Capacity (mAh): 4000

 Health Information:

 Cycle Count: 43

 Condition: Normal

 Battery Installed: Yes

 Amperage (mA): 1763

 Voltage (mV): 11855

System Power Settings:

 AC Power:

 System Sleep Timer (Minutes): 0

 Disk Sleep Timer (Minutes): 0

 Display Sleep Timer (Minutes): 10

 Wake on AC Change: No

 Wake on Clamshell Open: Yes

 Wake on LAN: No

 Current Power Source: Yes

 DarkWakeBackgroundTasks: 0

 Display Sleep Uses Dim: Yes

 GPUSwitch: 2

 Hibernate Mode: 3

 High Standby Delay: 86400

 PrioritizeNetworkReachabilityOverSleep: 0

 ProximityDarkWake: 1

 Standby Battery Threshold: 50

 Standby Delay: 10800

 Standby Enabled: 1

 TCPKeepAlivePref: 1

 Battery Power:

 System Sleep Timer (Minutes): 15

 Disk Sleep Timer (Minutes): 10

 Display Sleep Timer (Minutes): 10

 Wake on AC Change: No

 Wake on Clamshell Open: Yes

 DarkWakeBackgroundTasks: 0

 Display Sleep Uses Dim: Yes

 GPUSwitch: 2

 Hibernate Mode: 3

 High Standby Delay: 86400

 ProximityDarkWake: 0

 Reduce Brightness: Yes

 Standby Battery Threshold: 50

 Standby Delay: 10800

 Standby Enabled: 1

 TCPKeepAlivePref: 1

Hardware Configuration:

 UPS Installed: No

AC Charger Information:

 Connected: Yes

 ID: 0x1674

 Wattage (W): 30

 Serial Number: FNT85050M5CJV3FAD

 Name: 30W USB-C Power Adapter

 Manufacturer: Apple Inc.

 Firmware Version: 1020067

 Charging: Yes

The settings seem to me as being all correct. The one that Im not familiar with (or cannot seem to google either) os the Standby battery threshold 50.

Can anyone shed some light on this? Is there something that Im missing?

Thanks

W