Page not found

Watchdog keeps showing “page not found” warnings that repeat over and over again:

/calendar-field_data_evento/day/202107
/calendar-field_data_evento/202617
/calendar-field_data_evento/year/202116
/calendar-field_data_evento/year/202706

…………….

The site is not in production yet and I have only done a couple of tests. There is no content in the calendar at the moment.
I had the same problem on another site, but with the Calendar module, and here the module is not installed.
What could be causing this annoying problem?

Thanks and best regards