The horizontal resolution of the environment map used to light the model in the Render View, and shared with Connections, is 646 pixels by default. But this Proxy Map Size can be changed in the Preferences. Set it to 3000 for a (slower) high quality render with fewer jagged edges on lights. In the images below, note the resolution difference in the background.
Proxy Map Size 646 - Lower quality, faster
Proxy Map Size 3000 - Higher quality, slower