In my experience it’s generally best to roll out changes on testing, staging, and then clients in order of how much they pay, especially if you have SLAs with the highest paying customers.
Impact is generally lower, both to the client, and to your bank account.
That sounds strange to me. If you introduce a bug then roll back very quickly, it will only affect high paying customers. If you introduce a bug then roll back a while later, it will impact high paying and low paying customers equally. Why would you want this scenario? If you flip it it seems strictly better to me.
The idea is that the fix itself is being tested. If you knew your 'rollback' will work for certain, then you'd just deploy it to everyone asap. But since you don't, you test it and as a potential outcome of your test is no fix or making things worse, you don't test it on your highest-value customers. Imagine what your postmortem would read like if your fix made an even bigger mess.
I'm just describing what I think the sequence in the postmortem is. They were already in the poop and wanted to test their fix in a real but low-impact way.
Impact is generally lower, both to the client, and to your bank account.