I was donated an old MacBook Air and did a clean Monterey install to it via a bootable flash drive. Its default name was displayed in iCloud trusted devices. I then slightly changed its name via its Monterey Sharing > Computer Name (and Local Hostname as well). But it did not change in iCloud listing although I waited a few days in case a new router lease would automatically do that.
Today I booted that MacBook Air, signed OFF from iCloud, rebooted (just in case) and signed back to iCloud. THEN its new edited trusted device name was updated in the iCloud list.