Q.What’s wrong with my society garlic?
could it possibly be root rot? what should I do?

Certified GKH Gardening Expert
Probably. It does appear pretty wet in that spot. They are somewhat drought resistant, but they don't like to have "wet feet" for very long.
You will need to use a fungicide, and let the ground dry out very thoroughly down to AT LEAST 3 inches before watering again.
These articles will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
https://www.gardeningknowhow.com/ornamental/bulbs/society-garlic/growing-society-garlic.htm