The URI query is just a piece of string after the question mark. There is no global specification how it should be parsed etc.
HTML defined the usage of & , which is supported by CoAP, but implementations handle it differently, for instance, when a query parameter occurs multiple times.
For GET query filter should often rather use FETCH. In general better to use payload than query parameters. But OTOH bookmarking better with query params.
The URI query is just a piece of string after the question mark. There is no global specification how it should be parsed etc.
HTML defined the usage of & , which is supported by CoAP, but implementations handle it differently, for instance, when a query parameter occurs multiple times.