This means if you have hints off (via HOMEBREW_NO_ENV_HINTS) then I suspect you can start getting this behavior without warning which is a bummer.

When you instruct the system not to tell you things, the system not telling you those things is a bummer?

If I could get more of the tech I interact with to stop doing things I didn't ask it to, it would reduce a lot of stress and wasted time.

Ah, I suppose I did word that poorly—I more mean that a significant breaking change (Casks that previously were documented as being excluded from auto-updating suddenly being auto-updated) which can occur silently is a rough end-user experience, even if the user explicitly opted into hiding hints.