I first heard about this 0x20 scheme around 2015 when I was working on a DNS cache (also at Google, but not for the public DNS team). I noticed and had to work

I first heard about this 0x20 scheme around 2015 when I was working on a DNS cache (also at Google, but not for the public DNS team). I noticed and had to work around the fact that some servers were responding in vixie-case even when the requests were not. Those servers would be broken if the requests were paying attention to 0x20, right? I wonder what software was doing that.