Bastien,

the latest on the table header. With emacs -Q and org from a few
minutes ago, I get the following:

when I open the file, invoke M-x org-table-header-line-mode RET and
scroll down in the attached org file.

Note also that if I invoke the above command before opening an org
file, org complains (correctly) about the command not being suitable
outside org but then, when I open the attached file and invoke the
command again, I get:

org-table-header-line-mode: Symbol’s function definition is void: face-remap-remove-relative

Thank you.

eric

PS -signature out of date in this case. org up to date from 5 minutes
ago now.
–
Eric S Fraga via Emacs 28.0.50, Org release_9.3.2-198-g06d36e