Hello.
Thanks to everybody.
To avoid this kind of problem, we have completely disabled all types of automatic updates (https://codex.ww.wp.xz.cn/Configuring_Automatic_Background_Updates).
Sorry, I can’t give you the url.
Anyway, it won’t help you to know it : you would just see that in the HTML source code, the onclick is missing (but if I go to the back-office and add it in the post, it will appear again).
