[Résolu] .htaccess file automatic override which causes endless loop (causing 503 backend fetch failed error)

Background of the issue:
Our .htaccess file is by time to time overwritten by the WPML plugin (don't know when or why) which causes an endless loop in our website and a 503 Backend Fetch Failed error. This is how a standard .htaccess file should look:
# BEGIN WordPress

RewriteEngine On
RewriteBase /
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

# END WordPress

This is the example of the .htaccess file when we get the error:
# BEGIN WordPress

RewriteEngine On
RewriteBase /nl/
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /nl//index.php [L]

# END WordPress

Adding /nl/ by the WPML is causing this issue i think.

Symptoms:
503 Backend Fetch Failed error

Questions:
Is there a solution to prevent this from happening?