If you call the REST API using _embed parameter you will be able to get the embedded objects as "_embedded" JSON object of returned JSON as following:
/?rest_route=/wp/v2/posts&_embed
And if you use _fields parameter you can filter out the objects returned by API like:
/?rest_route=/wp/v2/posts&_fields=id,content,title
The problem is when both are_embed and _filter are used simultaneously the results returned do not contain "_embedded" JSON object no matter what combination of filter I apply. For example:
/?rest_route=/wp/v2/posts&_embed&_fields=id,content,title,_embedded
does not return "_embedded" JSON object
Worpress Version is 5.3.2 (Latest)
And pretty permalinks are not enabled so usage of "/?rest_route=" is mandatory