Holding down the whistle key for a second (because it can take a second for the whistle to happen... so it just seems natural)... can cause like 100 whistles to all happen at once... -- it feels like this causes some frame drops too when it happens.

I suggest adding some kind of concurrency detection (i.e. ignore the whistle key until the whistle is over -- that way if you hold it down, it will still whistle over and over... but not 100 whistles all at once).

Which version are you playing on? I fixed the whistle spam back in the 1.18 version, should be on 1.19 as well.

In MultiMC it says the version is "NONE". For Minecraft, I'm using 1.19.
The MD5 hash of the file I downloaded matches this one, so I guess I'm using 1.4.2:

oh its because the fix isnt on fabric. I'll get in touch with the fabric maintainer, and we'll get that fixed soon

This is also happening in 1.4.3 (Fabric).

Should be fixed in the latest fabric version. Let me know if it isn't and we'll get it fixed