Question: what is the use of the Background Counter Return Frequency setting? Does it impact battery?

[kaoneko]

With the default setting (of 1 hour or so?) the number of steps reported by the app would often not be accurate until later, and when restarting the app (e.g. to circumvent some bug or force dark mode with DarQ) it would never catch up, as if it was losing buffered steps, resulting in an inaccurate step count at the end of the day as well.

Since I set it to No delay allowed everything is working smoothly. Does this use more battery, or why is this even configurable and not just the only way the app operates?

[morckx]

This totally depends on the Android version. On more modern Androids, the value is ignored if it below a certain minimum.