For some unexplained reason, when going to the event selection page (using cal.com), I cannot select a date from the current month.
You may also try to switch views, e.g. to weekly view, still doesn't work.
When visiting the date selection page, it automatically navigates to the next month (February instead of January in this case), and does not allow to switch to January. Even when writing the URL specifically for the current month (January) it jumps to the next (February) rewriting the URL.
The following screenshot also shows that when manually entering the month in the URL, it switches to the next: