We're coming up on 40,000 miles with our 2017 Bolt as well, rotating tires every 5,000, and will probably need them at either 40 or 45K.I got 60,000 on the OEM tires on my 17 Bolt. Probably could have gone another 10k, but I don't like to push tires to the limit. I neither baby nor abuse tires, I'd say I'm pretty average.
Curious if they said it was uneven ware (indicates misalignment), Cupping (under inflation) or wear around the outside edges (over inflation). You can get a tread wear gauge for a couple of bucks, The the tires also have "wear bars", little raised areas in the tread pattern to show when maximum wear is reached. Duck Duck Go is your friend with this.
To the OP, my Model S is 1,000 lbs heavier than the Bolt and I've needed new tires every 35,000 miles, so there's a high likelihood of some extenuating issue causing such a rapid wearing of your tires.