As reported on #199689 in comments 93 [1] and 102 [2], if I have my Yubikey 5c nano plugged in, suspend doesn't work properly and the battery drains quickly. I'm opening this bug ticket as previously requested on that thread.

My test case:

1. reboot so idle counters are zero
2. plug in yubikey
3. suspend, wait a few seconds
4. wake
5. cat /sys/devices/system/cpu/cpuidle/low_power_idle_{cpu,system}_residency_us
6. observe both are zero
7. unplug yubikey
8. suspend, wait a few seconds, wake
9. cat /sys/devices/system/cpu/cpuidle/low_power_idle_{cpu,system}_residency_us
10. non-zero values

[1] https://bugzilla.kernel.org/show_bug.cgi?id=199689#c93
[2] https://bugzilla.kernel.org/show_bug.cgi?id=199689#c102