I've noticed this many times too, particularly recently, and I call it "Google Alzheimer's" --- what was once a very powerful search engine that could give you thousands (yes, I've tried exhausting its result pages many times, and used to have much success finding the perfect site many dozens of pages deep in the results) of pages containing nothing but the exact words and phrase you search for has seemingly degraded…
I also get very angry at Google trying to stop me from making advanced queries. Even if I only chain a couple of Google's very limited operators together it shows me captchas and after a while the captchas do not stop. I keep solving them and it just wants more. Lately I've also been noticing that the behaviour of some google search operators are broken. " something " "otherthing" is not considered as an AND " someth…
The loss of '+' is annoying, particularly since quoted and non-quoted mixtures are unreliable. Searching on "freebsd" "meltdown" might have solved your problem, but it's too unpredictable to be sure. My experience suggests that Google is doing something with site-level search, such that a site with only 'freebsd' won't appear but a site with 'freebsd' and 'meltdown' on different pages still might.
'-', meanwhile, seems to simply be disabled some of the time.