"dns-base" is one of the subsets of the "dns" application ID. The "dns" application ID is currently being split into to separate subcategories so those who want can filter non-compliant DNS requests:
dns-base: general DNS requests
dns-non-rfc: Non-RFC complaint DNS requests
You can see the descriptions of these application IDs on your PaloAlto under:
Objects -> Applications -> search "dns" and then click the dns application names
dns-non-rfc was introduced June 21 2022 and is scheduled for activation July 19 2022. You can read more here:
If your current Security Policies allow application ID "dns", that will include both subsets. If you only want to allow RFC compliant DNS traffic, then your Security Policy should only allow "dns-base" (non-RFC compliant will be excluded after July 19).
Since your current Security Policy set is denying DNS traffic, I would start looking at your current rule to allow "dns" or "dns-base". Is it applied to the correct zones, source/destination addresses, and using "application default" or "any" Service?
IMPORTANT EDIT: Re-reading the enhancement release now, there are recent comments that people using "dns" application ID had their Security Policy broken, they had to explicitly add the subset "dns-base" to get DNS working again. See this follow up article with release information:
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