Essentially the problem with HSTS is it's a malicious choice to remove user agency because the spec intentionally prohibits web browsers from allowing a bypass option, despite the browser being an agent of the user, not the server. It also tells you to talk to your administrator, which is unhelpful when you are the administrator but the browser refuses to allow the administrator to continue.
Every time I've encountered HSTS in practice, it's been because of a perfectly normal certificate error I'm aware of the reason for (usually expiration) and have no real concerns about bypassing, except my own web browser won't let me.
The problem with HSTS (and MTA-STS) is that these are specs designed for internet centralization, where Google or Microsoft controls everything and manages everything[1], and a certificate never lapses. It's not designed for the real world, and neither of these specs would've made it except for that big tech has complete capture of web standards.
[1] Didn't know who the authors were when writing this comment, but the authors of the MTA-STS RFC are in fact, Google, Google, Microsoft, Comcast, and Yahoo.
HSTS would be an annoyance, but still manageable if not for the complete removal of our user agency. I think that's really where HSTS moves from a security specification to an abhorrent abuse of monopoly control of web standards. It's less about protecting the user and more about giving Google and such power over what you can and can't view with your browser.
For any other certificate issue, my browser will allow me to bypass it if I know what I am doing. But because HSTS has hijacked the browser, it will no longer act in my stead unless I fork the browser and recompile it. I consider HSTS to be a malicious specification in this respect.
HSTS by specification prohibits browsers from offering that option. So I can know a server is serving valid, authentic traffic via HTTPS, be aware of why the certificate has an issue, and HSTS requires that my browser prohibit me from connecting to the server.
Are you sure you're not thinking of HPKP?