Comment by ajvs

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.

[1] https://www.dell.com/community/XPS/XPS-15-9570-BIOS-1-3-0-sl...