There is a very small percentage of mobile searches where Google only returns the first page of results.

We already faced this problem about a year ago:
https://feedback.trueranker.com/updates/mobile-searches-with-few-results

Now the percentage of searches affected by this has gone up (0.12%), so we have taken a decision about it.

If all our attempts to perform the search correctly on mobile fail, we will perform the same search on desktop.

Keeping in mind that mostly desktop and mobile positions are similar, this way we avoid losing that day's data if you are not on the first page.

The next day we will retry the mobile search normally.

This whole process is transparent to the user.