RewriteRule in .htaccess not working with Cloudflare APO

I need to display content of for the page is a wordpress for which I added the following lines in the .htaccess file:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
# Check if the request is for /app
RewriteCond %{REQUEST_URI} ^/app
# Proxy the request to
RewriteRule ^app(.*)$$1 [P,L]

When I am logged as an admin in the wordpress, everything works fine.
But for any other use case, is not found.
I strongly suspect that it comes from Cloudflare as I am using Cloudflare APO.

Any idea about how to solve this issue?