Starlight Mod (1.19.2, 1.18.2) modifies the light engine to correct lighting issues and improve lighting performance. Starlight can either be installed on the dedicated server, or on the client. You don’t have to install it on both the server and client. Clients can connect to Starlight servers by using Vanilla/Starlight if Starlight is installed on the server. You can also connect to Vanilla/Starlight servers if Starlight is on your client.
Starlight was designed for dedicated servers of higher scale, because they were experiencing performance issues due to Starlight’s slow light engine. A very intrusive mod was created that rewrote the entire engine.