Apple Silicon is "always on", it is not going to sleep for a long time like Intel's.
This behavior is not exclusive for M1, all iOS device already having this behavior for years.
Apple introduced "Power Nap" on Intel Macs, and that does the similar thing: periodically wake up the computer to perform background tasks. But on Intel processor this will drain battery like hell, so this is disabled as default on battery. But Apple Silicon can do this much more efficiently.
Such behavior has a benefit: the "instant wake up" cannot be implemented without an always-on processor.