Since at least the 2019 model Dell XPS 13s no longer have S3 sleep mode and instead uses Microsoft's "Modern Standby" (s0ix)[1], which consumes tons of power whilst in "sleep" in order to have slightly quicker wake times.
s0ix is fine so long as it actually activates. The problem is that in some default configurations it doesn't and you end up using a poorer sleep. On my 9305 it was a matter of changing a storage setting in the BIOS and afterwards it was perfectly fine. (If you'll pardon linking my own blog, I wrote about this particular issue a little while ago: https://thomask.sdf.org/blog/2021/08/15/debian-11-bullseye-o...)
On my Thinkpad x13 there was an option to use "Linux sleep" or something like that in the uefi (bios?) Settings. I think this just gives it the normal sleep behavior, and definitely reduced how often my laptop would come out of my backpack hot and on low battery (running Linux)
