...will use tactical nukes in Ukraine or anywhere else. The war in Ukraine has exposed how badly Russia's military equipment has been maintained. It can only be worse for nukes. Nuclear weapons are expensive The US spends more maintaining our nuclear weapons than Russia spends on its entire military, including their nukes. They can only afford to maintain a pretty small number of nukes, or to poorly maintain all of them.
That means that there is a high probability that many, most, or perhaps all of Russia's strategic nukes are of dubious reliability. Given that, that it makes it very unlikely that Russia wants a large-scale nuclear exchange with the West -there's a high probability that they would be wiped out, while causing little to no damage to the West. Using tactical nukes raises the probability of initiating that very exchange. If Russia was invaded and Moscow itself was threatened then they'd probably throw the dice. Short of that...not likely at all.
I doubt that that could have been known in 2014, probably even in 2022 it was speculative. But there can be little doubt in 2024 that Russia largely is a paper tiger whose only real military advantage is its willingness to sacrifice huge numbers of people.