With https://www.google.com/search?q=site:perlmonks.com+warnings, I only get 7 results, which seems very wrong.

What's worse - and this is an old problem - many results are for irrelevant variations like displaytype=print or showing the edit history

It's a pity we can't control the bots better.

FWIW: here an old workaround I'm using for Google (already for at least 10-15 years):

https://www.google.com/search?sitesearch=www.perlmonks.org&q=%22Node%20Type:%20perlquestion%22%20inurl:node_id%20-displaytype%20-index.pl

NB: by design it will only find complete threads.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery}

I don't have this problem with org domains:

https://www.google.com/search?q=warnings+site%3Aperlmonks.org

Probably depends on robots.txt settings and subsequent indexing.

Update

On a side note, my mobile Chrome can't use the site anymore when logged out.

So the choice of domain in the site-search has direct consequences.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
see Wikisyntax for the Monastery}

IIRC, something was added to specify that perlmonks.org or www.perlmonks.org is the official domain, so no surprise you get better result from that one.