Are you actually hibernating it, or doing the "hybrid sleep" thing, which only sleeps and then hibernates? In my case (Arch) the default for hybrid sleep is to keep it in sleep state for quite a while, whereas windows shuts down fairly quickly when unplugged.
Actual hibernation is shutting the computer completely off, so I'd be curious to know how one OS could have a different power consumption than another.
The way I found out is this one time I left work with my laptop under windows and asleep.When I arrived home an hour later, it had to go through the full bios setup (which you can't miss since it's ridiculously slow) and then it went and booted Linux (it's the default boot setup). When I rebooted back to windows, I found my previous stuff open. Since this happened again a few times, I figured it was normal behavior.
My default Linux install won't automatically hibernate while asleep as long as the battery is above some threshold, like 10%. And since the computer doesn't support S3, only "modern standby", it will chew through the battery like no tomorrow.
To diagnose hibernation issues, I'd double check the kernel command line (resume=<disk or inode>) argument. That it's still the right location.
It's a right pain as it means when I get an authentication popup I can't use my integrated password manager like I can with say Slack's authentication popups.
(yes I know that integrating browsers with pw managers are bad)
I switched my mother-in-law (nearly 70 years old) to a Chromebook and I made my SO switch her little PME from Windows to Ubuntu more than a year ago and she has zero issue.
As for the rest of my family, they kept calling me on the phone over the years with Windows issue and... I made them all buy Mac computers.
Life is better without Microsoft.