.htaccess settings for running Kirby as a headless CMS on a subfolder

Hello,

I use Kirby as a Headless CMS for a SPA. Therefore I run it on an Apache Server that is being served on the path /cms of my Cloudfront distribution.
All other requests are being routed to an S3 Bucket where the SPA is hosted.

So basically:

Kirby is reachable through the /cms path but only renders an error page.
I tried to change the .htaccess file and added the RewriteBase /cms directive. But this leads to an 500 Apache Server error. The server logs state that it’s ‘exceeding the limit of 10 internal redirects’.

This is my .htacess file:

# Kirby .htaccess
# revision 2020-06-15

# rewrite rules
<IfModule mod_rewrite.c>

# enable awesome urls. i.e.:
# http://yourdomain.com/about-us/team
RewriteEngine on

# make sure to set the RewriteBase correctly
# if you are running the site in a subfolder;
# otherwise links or the entire site will break.
#
# If your homepage is http://yourdomain.com/mysite,
# set the RewriteBase to:
#
RewriteBase /cms
# In some environments it's necessary to
# set the RewriteBase to:
#
# RewriteBase /

# block files and folders beginning with a dot, such as .git
# except for the .well-known folder, which is used for Let's Encrypt and security.txt
RewriteRule (^|/)\.(?!well-known\/) index.php [L]

# block all files in the content folder from being accessed directly
RewriteRule ^content/(.*) index.php [L]

# block all files in the site folder from being accessed directly
RewriteRule ^site/(.*) index.php [L]

# block direct access to Kirby and the Panel sources
RewriteRule ^kirby/(.*) index.php [L]

# make site links work
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*) index.php [L]

</IfModule>

# pass the Authorization header to PHP
SetEnvIf Authorization "(.*)" HTTP_AUTHORIZATION=$1

# compress text file responses
<IfModule mod_deflate.c>
AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE application/json
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript
</IfModule>