If enabled, players and their own weapons are transmitted for the first x ticks when they had a full update.
While a player is within their own full-update window (see holylib_networking_transmit_ticks), all of their weapons are transmitted to themselves every tick, and every other player entity is force-transmitted to them so they immediately know about everyone on the server.
If the recipient isn't the one in a full update, holylib_networking_transmit_onfullupdate_networktoothers decides whether other players who are currently in a full update get force-transmitted to them as well.