I'll respond to this comment but there are a number in the same vein: "Russia would still have X% working nukes even if Y% don't work, and they have lots of nukes."
That is true. However, what's missing from this assessment in my view is the difference between strategic nukes (the kind that level a city) and tactical nukes (the kind you use for specific tactical goals, and the only kind being discussed as likely to be used here).
Russia has enough working strategic nukes that any kind of direct offense against the Russian homeland is always gonna be off the table. That is totally true. But nobody, including Russia, has suggested those are going to be used at all.
Rather, what is contemplated is using a tactical nuclear weapon to make a statement or accomplish a specific wartime goal. With regards to tactical nukes specifically, I think this claim:
> 5% still working is enough to deter NATO from directly attacking Russian forces.
is possibly not true. I think NATO might be willing to engage Russia conventionally if it is clear their tactical nukes don't work - and maybe even if they do work, because that may be among what has been threatened as a response to the use of a tactical nuke.
If Russia threatens to bomb Warsaw or DC, the situation changes again. But nobody has put that on the table... yet.