Last Friday, Google suddenly removed many web pages from the search results. It turned out that this was an error and Google tried to fix the problem:
We're aware of indexing issues that impacted some sites beginning on Friday. We believe the issues are mostly resolved and don't require any special efforts on the part of site owners. We'll provide another update when the issues are considered fully resolved.
— Google SearchLiaison (@searchliaison) April 7, 2019
Just a short update on this — indeed, it does look like there are still some pages that need to be reprocessed. Our systems are making good progress here, but it's taking longer than I initially expected. Using Inspect URL + Submit to index is fine, if you want to do that.
— ? John ? (@JohnMu) April 7, 2019
Optimize your pages now
Although not all page rankings have been restored yet, it seems that Google has fixed the problem. To make sure that Google ranks your web pages as well as possible, optimize your website with the tools in SEOprofiler: