It was https://threekit.com. It was a while ago now but we had to use MySQL for our primary copy that users used (e.g. prod), and only when they were working on branches did we use dolt. I think the second complication was that Dolt was not stable enough to use in heavy load scenarios as well.
I can delete this comment if you do not want to discuss this publicly.
I remember that engineering decision. You guys were pretty early customers for your throughput and durability requirements (we hadn't even added standby replication yet when you started your integration). We've come a long way in the years since then.
https://docs.dolthub.com/sql-reference/benchmarks/latency