Adding to my comment on my XPS13 7 days ago: * I raised a service ticket with Dell. * They asked me to install the latest firmware for the XPS13 9310, dated 8

Adding to my comment on my XPS13 7 days ago: * I raised a service ticket with Dell. * They asked me to install the latest firmware for the XPS13 9310, dated 8 April 2021. * That solved the problem: now I can close the lid and the laptop properly sleeps; I can put it in my bag without it getting noticeably warm; battery loses just a couple of % overnight, not 75% as it did before. So irrespective of whether this 11th gen does S3 sleep or not, my laptop is now performing in line with what I expected. Thus: thank you Dell.