MacBook Air battery drain during sleep & tcpkeepalive

I've noticed that my 2017 MacBook Air will lose 10-20% of its battery at night sometimes even while it's sleeping. I don't remember having this trouble with other Macs.

Looks like I'm not alone. Here's a thread on MBPs with the same issue.

$ pmset -b tcpkeepalive 0
Warning: This option disables TCP Keep Alive mechanism when sytem is sleeping. This will result in some critical features like 'Find My Mac' not to function properly.
'pmset' must be run as root...
$ 
$
$ sudo pmset -b tcpkeepalive 0
Password:
Warning: This option disables TCP Keep Alive mechanism when sytem is sleeping. This will result in some critical features like 'Find My Mac' not to function properly.
$ 
$ 
$ pmset -g
System-wide power settings:
Currently in use:
 standbydelaylow      10800
 standby              1
 halfdim              1
 hibernatefile        /var/vm/sleepimage
 gpuswitch            2
 powernap             0
 disksleep            10
 standbydelayhigh     86400
 sleep                5 (sleep prevented by sharingd)
 autopoweroffdelay    28800
 hibernatemode        3
 autopoweroff         1
 ttyskeepawake        1
 displaysleep         5
 highstandbythreshold 50
 acwake               0
 lidwake              1

So the OS knows about this option, even though tcpkeepalive doesn't appear after a pmset -g.

I don't know. I saw this a couple of places, the terminal seemed to admit its existence, and I'd like the laptop to sleep without losing power. We'll see.