I don't recall. Like the other reply to you says, these get leaked in support, etc. I'll also run "strings" or even Ghidra on closed-source binaries when I'm troubleshooting issues. There's usually good fun to be had from Microsoft binaries doing that. I've discovered undocumented debugging switches, registry entries, etc.

(In version 10.0.19041.985 of cscsvc.dll in Windows 10 I'm seeing the string "If you hit this breakpoint, send debugger remote to BrianAu." Presumably that's "Brian Aust", referenced in a chat[0] re: Offline Files.)

[0] https://techcommunity.microsoft.com/t5/storage-at-microsoft/...