I am not sure Home Depot is getting rid of Rusto, I think there is just a paint shortage right now due to COVID. Yet another COVID casualty (how COVID caused an Iced Tea shortage, I still haven't figured out!)
Paint shortage is well documented. Most available production is going toward home builders/commercial developers right now since they need literally hundreds or thousands of gallons of paint to complete small and large buildings. Despite any media coverage to the contrary, skyscraper construction in NYC has continued unabated throughout COVID.
The paint shortage has been going on since Spring, but is just now hitting the consumer due to a large supply of rattle cans manufacturers already had on hand.
Like most of the shortages these days, don't hold your breath on the supply coming back anytime soon.
http://www.paintmag.com/update-paint-shortage