There was an update today.

I didn't get an update today. That said, I believe you, but I can't speak to the stability guarantees of your software provider unless you name (and shame!) them.

I doubt this would be considered a release-critical bug in Debian, so it is certainly possible for breakage like this to occur between releases. If it was a security issue, then ... I hope you are assuaged that your old way was a vulnerability that needed to be disabled for your safety. While distributions and developers try to avoid such breakage, sometimes it is inevitable or just the result to trying to minimize the vulnerability window, chronologically speaking.

I do think that MS Windows users got surprised when their Notepad experience changed unexpectedly recently. Maybe you don't consider that equivalent, but it is instability.

Anyway, my experience is that Debian Stable is more stable than the MS Win 10 laptop issued by my previous employer. And, I don't know of any rigorous studies comparing the Linux stability with MS Win stability, so I'll tend to prefer to be guided by my experience. (And, I don't expect you to abandon your experience in favor of my anecdotes.)

(Honestly, I'd probably still be using Free Software even if it was less stable that Proprietary Software, but I am glad Debian Stable does focus on stability and I do support most of the policies they use to implement it.)