[Resolved] WPML rewriting .htaccess, adding /de/ despite my default language is just / (EN)

Background of the issue:
I am trying to avoid my site going down at least once a month, presumably after WPML updates, because .htaccess is rewritten. My default language is English (EN) with no language path, and German (DE) is set as a secondary language. I expect my .htaccess to remain the way I set it and only change after I approve the suggested changes. The issue is exactly the same as this ticket: https://wpml.org/forums/topic/wpml-modifying-htaccess-file-2/. My site structure is hidden link for English and hidden link for German.

Symptoms:
My .htaccess file is being rewritten to include /de/ in two lines, causing a 500 response across my entire website except the homepage. The original .htaccess should not have /de/ in the RewriteBase and RewriteRule lines.

Questions:
Why is WPML rewriting my .htaccess file to include /de/ despite my default language being English?
How can I prevent WPML from automatically changing my .htaccess file without my approval?