The big problem in using a movie based recording system is that inter frame compression ends up as artefacts on extracted images. The artefacts are actually very large compared to the resolution so 4K isn’t actually a good sell point. In fact a “better codec” that yields smaller files/time actually has more artefacts than one that doesn’t compress as much.
When Mapillary modified the BlackVue firmware to record at a lower frame rate, the bit rate didn’t fall by a proportional amount. The resultant movie now has less artefacts and are noticeably sharper than the default 30FPS model firmware.
The tech specs for the 70mai are not very forthcoming in this area.