Unfortunately, imo this does sound as the start a new serious escalation. I could be wrong, but they really don't like the continued support Ukraine is getting and want to stop that. Especially extra aid and maybe in this new phase , support coming from influx of extra military from abroad.
Also, according to internal rumors in Russia, their war economy is slowly killing their home economy. Lots of domestic business are closing shop, and many people have been working in warfactories. Also when planes, trains and other stuff massively starts falling apart, something which already has been happening, they won't be able to maintain the supply lines.
So probably very soon (summer) we'll see a very heavy offensive from 2 or 3 sides, and they really don't want extra trouble, as apperantly this wars costs are trememdous in their scale.
The longer it takes, the lower the win chances for Ruzz will become, though I wonder atm, if anyone in the top even knows what their actual plans could be. I surely don't hope something like " If we can't have it, nobody will" , like Stalin did, and they'll turn the place into a wasteland.
Fyi via ap ap link
"It was the first time that Russia has publicly announced drills involving tactical nuclear weapons, though its strategic nuclear forces regularly hold exercises. Tactical nuclear weapons include air bombs, warheads for short-range missiles and artillery munitions and are meant for use on a battlefield. They are less powerful than the massive warheads that arm intercontinental ballistic missiles and are intended to obliterate entire cities."