Bug Report

Describe the bug
Unable to run apt update. Get error NO_PUBKEY 9F9DDC083888C1CD

Err:3 https://packages.fluentbit.io/ubuntu/focal focal InRelease
The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 9F9DDC083888C1CD

OS Details

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal

Trying to install fluentbit version 3.2

To Reproduce
Following this link https://docs.fluentbit.io/manual/installation/linux/ubuntu
to install

Additional context
I tried to import apt-key add but not work this extra effort.