What's super annoying is that Dell does not provide a BIOS option to switch between connected standby and S3. It's likely a cost saving decision because S3 is more complex to implement and having both options even more so. There are also some rumors that Dell may be under contractual agreement with MS to only support connected standby.
Psst. On certain motherboards Dell just removed the option from the UI but the implementation is still there. They also oh so helpfully store their config in EFI variables so... If you're lucky you can just flip the right bit and enable S3 sleep again. For example the G5 5505 has it in D01SetupConfig and you just need to find the right offset that corresponds to it. https://www.reddit.com/r/DellG5SE/comments/kpg3ez/how_to_dis...
