ERROR 500

Last update made it happen again…
Besides changing permission to .htaccess to 755, how can I stop this plugin from changing this?

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

if I don’t set it to 755, which the above code in .htaccess, the moment I change language on the website back and forth, I get critical error 500.

Why does swapping language change the .htaccess? This shouldn’t be the case, especially as it’s a global file, not a per-visitor related one.