There is a change in licensing infra from 20.3R1 onwards where device expects the license key to be using agile key format instead of the legacy format and hence this error logs are seen.Below Link can be referred for more details on above :-
https://www.juniper.net/documentation/en_US/junos/information-products/topic-collections/release-notes/20.3/jd0e18951.htmlThis however does not have any funtional impact and the licenses are still valid and in use and no mitigation is needed .However to suppress these logs license needs to be installed with agile key.Below Link can be referred for steps on how to activate Agile license on the device :-https://www.juniper.net/documentation/us/en/software/license/juniper-licensing-user-guide/topics/topic-map/activate-license.html#:~:text=Log%20in%20to%20the%20Juniper,Click%20the%20Activate.