Woah did you figure out what caused your ultrafines to burn out this way? My 5k ultrafine has lived through maybe 5 various work and personal MacBooks over the years, and I never had issues with it.I burnt out three LG Ultrafines that way recently. First one lasted a little under a year, sent it back for repairs and it burnt out in only dive weeks. Replaced it with a new one it lasted a little over a week, the replacement less than 24 hours.
Right now typing this on the Asus Proart 4K 32" as I didn't have the budget for the 6K nor the patience to wait as I need a monitor for work.
I hope your mac is okay, I imagine that would be a nightmare to try and get a third party to pay for your computer's repair bills.