It is, but they had some "checklist" that included "block paste" for reasons unknown, and so they blocked pasting.

In firefox, if you change the about:config setting "dom.event.clipboardevents.enabled" to false you'll be able to paste no matter whether the website operator has "block paste" on their braindead checklist or not.

However, I have noticed that, on some fields, the field rejects certain input without any message if the input is not the correct intended field type. For example, copying a numeric one time password from an email which gets copied as string and pasting on a field which only accepts numbers. This might look like paste blocking but its not.