Do Not Disturb Icon has disappeared

iOS 14.6 updated:

Recently my 12 mini did not have any response when someone else made a phone call to my phone.

i contacted the local telecom service and the 4G system had no problems at all.

the service clerk has suggested to have a new SIM card.

later i found that my DoNotDisturb was on.

the problem is that it didn’t show on the top of my screen, neither next to the battery icon, nor to the corner of time.

the status of the DoNotDisturb icon, a moon, should be always shown as previous iOS version when it’s switched on, instead of disappearing without notifying the users.

i wonder whether others had the same issue or not.

thanks

tim