I think you may be misinterpreting the way the funnels work here @Pawel Antoniak. If you have a 2-step funnel, you’ll observe a flow rate from A to B. As soon as you put steps between them, let’s say D E F, the conditioning completely changes in that B will only count if A then D then E then F occurred beforehand….so it’s perfectly understandable that the “overall” conversion rate would be different (i.e. the 2-step funnel doesn’t care what may or may not happen between the steps).
The key here is whether you expect intermediary steps to be mandatory/ truly unavoidable. For example, in your case are all of App_Onboarding_view, Onboarding_undefined and mobileApp_survey_submission mandatory steps in the flow? I’m guessing possibly not, which will completely explain why the 67.1% differs to the 53.1%.