reported in https://forum.matomo.org/t/disable-custom-ranges-in-compare-to-feature/36294

When one sets

enabled_periods_UI = "day,week,month,year" # without range

the date selector hides the possibility to select a date range, but it still allows comparing to date ranges (which will succeed as the API is used).

when one also adds

enabled_periods_API = "day,week,month,year"

the UI still allows the comparisons, but the user will only see errors:

The period 'range' is not supported. Try any of the following instead: day, week, month, year