Versions: 
roundcubemail-1.4.9-2.1.noarch (updated 2020-12-15, yesterday)
lighttpd-1.4.55-4.1.x86_64
apache2-2.4.46-9.1.x86_64

roundcubemail newly requires lighttpd by name.  On my webserver,
Apache is the HTTP infrastructure that sends out RoundCube.  
I hit some snarl-ups with both lighttpd and apache2 installed
together (my hacks, not your fault).  I wanted to just de-install
lighttpd, but roundcubemail has a hard requirement for it.  So
instead I'm fixing the snarl-up and letting lighttpd sit unused,
until it's no longer required.  

Lighttpd is a nice package and I used it on a project where a 
lightweight webserver was needed, but in this case roundcubemail
needs to defer to the sysop's choice of webserver.  Could you
please refer to "httpd" as the facility needed by roundcubemail
rather than picking a specific one of the various available
webservers?  Both apache2 and lighttpd provide this generic
facility, and I assume that nginx does also.  

Also, it's a little bizarre and inefficient to install 
roundcubemail on a different host from the webserver and then
make it available to the webserver on a SAN-like kludge like NFS,
but that kind of baroque storage architecture seems to be the name
of the game in the enterprise today.  I'd also like you to change
"require" to "recommend" to accommodate situations like that.  

I'm surprised not to see any hits in a bug search for 
"roundcubemail lighttpd" that I could add a "mee too" comment to.