Hello,
thank you for the report. From your description, it looks like the speed provided by the phone’s GPS is fluctuating slightly, which affects the automatic zoom level. Please check that Mapy.com has permission to use Precise Location.
In the latest versions of Mapy.com, this should no longer cause the map to continuously zoom in and out, as we have already fixed a related issue. If it still happens, please send us a report directly from the app. The diagnostic data may help us identify what is causing the problem.