I can't say I'm surprised, TBH. I had a rough idea of where the problem might lie just by reading the title of the post. But I was fortunate enough to do an undergraduate degree where concurrency was actually taught, plus I've learned a lot over the years working in highly-concurrent, asynchronous environments.

Concurrent programming has been mainstream for some time now, but I don't think the level of expertise of most engineers has kept up. That becomes most apparent when software starts hitting concurrency pitfalls: performance problems, deadlocks, UAFs, and so on...