Its not a limitation of infinity free. As people have done this before and it’s worked.
you’re not trying to remove the ?i=1 in you? because if your .htaccess does that it’ll be blocked (I cant see anything that would do this, but thought I’d check)
I used this thread, and the example works for my site:
RewriteEngine On
RewriteCond %{SCRIPT_FILENAME} !-d
RewriteRule ^([^.]+)$ $1.php [NC,L]
please note this doens’t make the php extention automatically vanish. It just means that when writing out the link, you don’t need to include the “.php”
For me, that meant a full rewrite of my site to update the links haha. But it was worth it
Remember that caching can cause problems too. you may need to clear your cache, or use an incognito session on your browser to see the change.