Hello Ghislou !

It seems the reason is in this repeatable trouble:

[Tue Sep 29 20:51:46.908111 2020] [:error] [pid 25253:tid 140686644438784] [client 82.242.221.40:36170] [client 82.242.221.40] ModSecurity: Output filter: Response body too large (over limit of 1048576, total not specified).

So you may try to add the following code to the .htaccess file:

<IfModule mod_security2.c>
SecResponseBodyLimit 546870912
</IfModule>

Or ask your hosting how to increase this limit.