- Server operating system version
- Debian 11.11
- Plesk version and microupdate number
- Plesk Obsidian 18.0.67 Update #3 Web Host Edition
After searching and reading all related posts on the forum, my question remains unanswered.... 
Could someone explain how PHP-FPM served by Nginx vs. Apache works?
The two setups I am testing are:
1. FPM application served by Nginx
Proxy mode = ON
Smart static files processing = ON
Serve static files directly by Nginx = ON
Enable Nginx caching = ON
The phpinfo() output shows: $_SERVER['SERVER_SOFTWARE'] => nginx/1.26.2,

and .htaccess works normally!
2. FPM application served by Apache
Proxy mode = ON
Smart static files processing = ON
Serve static files directly by Nginx = ON
Enable Nginx caching = ON
The phpinfo() output shows: $_SERVER['SERVER_SOFTWARE'] => Apache,

and .htaccess works normally!
The only difference in the setups is nginx / Apache.
For testing, my .htaccess file only contains: Options -Indexes
If I disable Proxy mode, the processing of .htaccess files stops, but in all other cases, it works normally.
Is this the expected behavior, or am I missing something fundamental ??
Could someone explain how PHP-FPM served by Nginx vs. Apache works?
The two setups I am testing are:
1. FPM application served by Nginx
Proxy mode = ON
Smart static files processing = ON
Serve static files directly by Nginx = ON
Enable Nginx caching = ON
The phpinfo() output shows: $_SERVER['SERVER_SOFTWARE'] => nginx/1.26.2,

and .htaccess works normally!
2. FPM application served by Apache
Proxy mode = ON
Smart static files processing = ON
Serve static files directly by Nginx = ON
Enable Nginx caching = ON
The phpinfo() output shows: $_SERVER['SERVER_SOFTWARE'] => Apache,

and .htaccess works normally!
The only difference in the setups is nginx / Apache.
For testing, my .htaccess file only contains: Options -Indexes
If I disable Proxy mode, the processing of .htaccess files stops, but in all other cases, it works normally.
Is this the expected behavior, or am I missing something fundamental ??