[racket] 5.3's "mzc optimizer" log-debug, and log "facility" in general

I have some code with copious log-debug calls. Occasionally I set
",log debug" to see the output.

New in 5.3, I'm seeing many dozens of outputs like the following:

; [debug] mzc optimizer: inlining: involving: core727 in: unpack728 in
module: 's3 size: 149 threshold: 320

These are interleaved with and badly obscuring my own debug output.

I've been trying to ignore these and live with it the last couple
weeks, but it's proving difficult.

1. Narrow question: Is there a way I can disable the mzc debug output,
while preserving my own?

2. Broader question: Do the logging functions need a "facility" or
"scope" qualifier? Because otherwise, when I share a collection, won't
I be inflicting my own debug output on someone else; they'll grumble
at me like I'm grumbling now?

(For practicality, I think this should NOT be some new optional
argument to log_xxx. Instead I think it should automagically be tied
to the name of the module or collection?)

Thank you.