Strange behavior of datetimepicker widget

When you click on the date selector, the calendar is displayed but it is placed behind the fields that are present on the screen and a scroll is added in the section to which the calendar widget belongs. I thought it was a consequence of what I added in my custom.css, however I noticed that the same thing happens in the demo

How to solve it? I thank you in advance.

That’s why we replaced the widget in 6.0.

And maybe there is some way to patch the issue until I can migrate to version 6.0?

You could certainly give it a go, but it’s probably just easier to upgrade to version 6.0.

The dependency got removed in Issue 9922: Remove tempusdominus dependency - Tryton issue tracker, so you would need to do something similar yourself to the version you are using.