Query parsing ignores rest of query when 'v' local-param is used

One of Solr's nasty/tricky gotchas is debugging a query that looks like this:

q={!parser v=queryString} OR ignored

Because this query string starts with {! and it has a v local-param, it means everything after the first } is ignored!
Experienced Solr users figure out to put a leading space on this as a hack. I've had to explain this several times and, really, Solr should fix this. Basically, if there is text following that bracket, then parse the whole string using Solr's lucene query parser which can recognize embedded queries like this.

Example of a confused user:
https://stackoverflow.com/questions/70658152/showing-parents-without-children-in-solr-search-too