I think maybe different brands may have different standards.

Re: mobile app differs from desktop app
I think there may be several reasons
Measurement location and accuracy: The location of different devices may have an impact on the accuracy of waveform data. Data viewed through a mobile device may be closer to the actual measurement location of the wave, while a desktop device may show more general or overall data.
Data sources and providers: Different applications and services may use different data sources and providers. This may explain the differences in data that exist between devices. Different providers may use different data collection and processing methods, leading to differences in results.
Device screen size and resolution: mobile and desktop devices have different screen sizes and resolutions, which may affect the accuracy and detail of data visualisations. Larger screens may show more data and detail, while smaller screens may only show part of the data.