The https://reference.opcfoundation.org/Core/Part14/v105/docs/A.3.2 defines http://opcfoundation.org/UA/PubSub-Layouts/JSON-Minimal HeaderLayoutURI and gives an example
...
"Active":true,
"Temperature":25.5,
"Counter":0,
...
In the old encodings (now listed in https://reference.opcfoundation.org/Core/Part6/v105/docs/H.8) that was possible due to the Variant having the line: "For the NonReversibleEncoding, Variant values shall be encoded as a JSON value containing only the value of the Body field. The Type and Dimensions fields are dropped. Multi-dimensional arrays are encoded as a multi-dimensional JSON array as described in H.9.".

That line is missing from the new COMPACT/VERBOSE encodings. I could only find the Part 14 saying in https://reference.opcfoundation.org/Core/Part14/v105/docs/7.2.5.4:
"If the FieldEncoding1 is FALSE in the DataSetMessageContentMask, the Variant at the top level of a field is encoded as a JSON value containing only the value of the Body field. If this Variant contains an ExtensionObject, the ExtensionObject shall be encoded as a Structure without the UaTypeId field. This also applies to the Variant in a DataValue at the top level of a field."
It should be noted that the field is now 'Value' and not 'Body', unless that text is also talking about interop with the old formats.

The https://reference.opcfoundation.org/Core/Part6/v105/docs/5.4.1, has mention of "The VerboseEncoding also supports the RawData mode..." that UaType + UaTypeId fields are excluded (btw, could this be used with the COMPACT encoding?), but that leaves the JSON Object with sole Value field (+Dimensions for multidim fields) like:
...
"Active" : {
"Value" : true
},
"Temperature" : {
"Value" : 25.5
},
"Counter" : {
"Value" : 0
},
...

In my opinion most likely the RawData format should be specified that the 'Value' field of Variant is in-lined (for the top-lvl Variants) for scalar and 1-dim array cases (and for multidim it should be what would currently happen, JSON object with Value and Dimension fields of the Variant).