Currently /v2 is a hardcoded alias for /v2/collections (but similar aliasing is not done for _introspect.
It would be more useful to reserve /v2 as a generic entry-point that works both in cloud and standalone mode. Perhaps instead that endpoint should report something similar as bin/solr status, i.e. version, node name, cluster size (nodes) and status (red/green/yellow), number of collections, number of local cores and a simple help text for how to use the API?
SOLR-10410 /v2/_introspect doesn't work