More data now:

*Some* white cis men have had technical interview ambushes, but only a few times (or once). *Many* have had expected technicals turn into casual chats.

*Many* to *most* URMs have been ambushed by technical interviews. *Very very few* have had casual chats instead https://twitter.com/alicegoldfuss/status/1263537556924198912

So, technical interview ambushes seem to be very common throughout the industry, but they are *more common* for URMs and *less common* for white cis men

I see quite a few people in that thread saying "well, if they do that to you, you don't want to work there!"

many people don't have that choice

"this is really toxic!"

yeah, we know

and it's likely it happened to your coworkers, perhaps at the company where you work