I agree with rainborick that hreflang isn't the issue. I'm thinking, though, that the issue might be the change that Google has recently made to how users choose what results they see.
Previously, if users viewed results on, say, google.de, they would see results 'localized' to Google in Germany, regardless of user-location when they viewed these. Now, that localization is no longer determined by the ccTLD of the Google search site a user is viewing, but rather by the location of the searcher.
So, as I understand it, if you are now monitoring your Google.de results from, say, the UK, you would be seeing UK results, not DE results. I've tried this from the US, and what serps I see when I do this are not precisely clear-cut. According to Google, you can still monitor your DE results, but to do so you need to make that choice via your Search Settings.
See our discussion here... Country-specific Google sites now all searching my local country Oct 27, 2017 https://www.webmasterworld.com/google/4874425.htm
In the thread cite Google's article describing the change... Making search results more local and relevant Evelyn Kao, Product Manager
Published Oct 27, 2017
To repeat what I'd quoted previously...
...the choice of country service will no longer be indicated by domain. Instead, by default, you’ll be served the country service that corresponds to your location....
If for some reason you don't see the right country when you're browsing, you can still go into settings and select the correct country service you want to receive. Typing the relevant ccTLD in your browser will no longer bring you to the various country services—this preference should be managed directly in settings. If for some reason you don't see the right country when you're browsing, you can still go into settings and select the correct country service you want to receive. Typing the relevant ccTLD in your browser will no longer bring you to the various country services—this preference should be managed directly in settings. In addition, at the bottom of the search results page, you can clearly see which country service you are currently using.
"Clearly" may be an overstatement. I've not had time to revise my settings, though, to test this. For Google.de from the US, the results without changing the settings seem to be semi-localized to Germany, but not what I've experienced before this change was made.
If you give this a try, please report back about what you see. You will need to be signed into Google for the settings to be noted.