It probably isn't. But as their business depends on software, it's worrisome that rather than understanding what was wrong, they just switched software. That doesn't seem inspiring to me.
Nobody said they had to fix the problems, but identifying them, and checking if they were fixed upstream seems like a good idea. Sometimes upgrading is a nightmare and doesn't fix anything, sometimes it fixes a major issue and drops cpu usage from 90% to 5%. If you know what the problem areas are, it should take less than a day to look at the changes and see if that area was addressed. Even if not, reading the changelogs and version notes should give some idea. It's fine if they didn't test upgrading, but again, I'm not inspired about their engineering talent and processes when it looks like they didn't even look to see if it would have been likely too help.
This will probably not be a popular opinion here but the business of DoorDash is not to fix open source software.
I get your point. I use a lot of OSS in my business and we do contribute back. But not every business has the opportunity to observe the stack for days or weeks while the real clients suffer due to outages. Each client who is affected by an outage is most likely churning immediately and you're not going to win them back easily.
In essence, the migration to Kafka will only benefit them long term and they have ultimately made the right business choice.