Yep, it's confirmed that Gojo died to Sukuna using a Binding Vow to use an instantenous World Dismantle... at the cost of needing to use certain hand signs and calls to do it again...
The person themselves state it but Binding Vows are so goddamned arbitrary to the point they don't even begin to make sense and I don't even mean Gojo's death, just why the fuck aren't people spamming Binding Vows and why the hell aren't they equal?