Thanks for your suggestion.

This request has been added to the tracker:
Issue 1823 – Optionally use Ctrl+F4 to close session tab

76 out of 87 applications use [m]Ctrl+F4[/m] to close, whereas only 4 of 87 use this shortcut for sorting.
(source https://defkey.com/what-means/ctrl-f4)
Perhaps you would consider changing [m]Ctrl+F4[/m] to close current tab?
If not hard-coded so perhaps by customizable setting :-)