M. Pger writes:
> Thx for your answer. I've just upgraded org-mode (elpa way) and I am 
> now using version 9.5.2.

Version 9.5.2 should indeed contain the fix I had in mind :

https://git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/?id=c91271297dbbfc831874d7880343603881bdac9c

> Unfortunately this does not work, I still end up with:
>
> Invalid read syntax: "#"
Can you check that the right version of org-mode is picked-up, with
`describe-function` `org-latex-export-to-pdf`, find the function
definition by following the `ox-latex.el` link, and check that the
source contains the linked patch ?
> I would like to try the alternative, i.e. disabling native-comp (for 
> the export function I guess). Would you mind telling me how to do that?

`describe-function` should also tell you whether the function is
native compiled. If it is, you can temporarily 'uncompile' by
evaluating its source code. By disabling native compilation I meant as
a compile flag, if you've built emacs from source. I cannot find an
easy way to prevent native compilation of a single package/function.

-- 
Sébastien Miquel