Dated is editable and the booking has been accepted with wrong dates. Why?

I have selected the dated 20th July 2021 in the WP Hotel Booking plugin calendar and then manually edited it (just to test it is a customer) and it allowed me to do so. Then in the next Check- out section, I manually entered some old dates and it accepted that as well. Without showing any error message it proceeds with a $0.00 order amount. I was able to place the complete order without any issue. No, where it prompted me for the wrong date pattern or selection. And not even for the order amount. This is something that needs to be fixed on priority.

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