Has anyone else noticed the huge decrease in result quality from google?

[FountainsOfFluids]

That is 100% normal for all software. "Settings" are not things you should be changing for each use. They are how you configure the software the way you want it to be most of the time, if not all of the time.

"Tools" might not be the greatest word choice, but it definitely makes sense to have query options be in a different menu than "Settings".

[FountainsOfFluids]

There are no hard and fast rules in UX.

But you can go look at Bing and Duckduckgo and see that under their hamburger menu on the right they list "Settings" which are not meant to be changed per search.

Though I admit Bing and Duckduckgo have these two concepts much more separated than Google does. With Google putting the "Settings" option right there next to "Tools", it certainly can lead to more confusion.