So what happened to the halo rings after halo 3?

I don’t know much about the halo lore so I’m sorry for asking a stupid question but as the title says, what happened to the halo rings? The main objective was for the humans to stop the great journey from happening which they did. Hence the name halo I guess. But now halo 4,5 aren’t even about the rings and haven’t mentioned them at all. Why is that?

I think the Halo rings were all destroyed.

Halo isn’t just about Halo rings, it’s much bigger than that. It instead revolves around the Forerunner artifacts in general.

They are being located and decommissioned, you see gama halo during Halo 4 and is where the UNSC found the composer

After Halo 3, the rings’ standby mode was disabled, and everything pretty much went back to normal, except for Installation 04, which was still destroyed.

Installation 05 was partially glassed by the Covenant due to the Flood.

In Halo 4, they reveal that the UNSC is attempting to locate the remaining Halo rings and study them for decommission. There is a base around Installation 05.
Installation 03 was discovered and had a base set up, but events in the Escalation Comics had caused the ring to be moved to an unknown location for repairs.
Installation 07 has been discovered as well and is being studied.

In 2555, all the remaining Halos were put into activation mode from the Ark, prompting a joint UNSC-Sangheili team to travel to the Ark again and shut them down.