Why the continual bombardment while having the peace talk?

Since the war started, Ukraine and Russia have gone through 2 rounds of negotiation, and I believe that the third round was done during the weekend. 

 Under normal circumstances, both sides requires a cease fire before talk can begin as a sign of good gesture. In the Ukraine-Russia talk however, the war rages on and even intensified in many cities after the talk, the only agreement made in the peace talk, the humanitarian path for civilians , was immediately violated by Russia. 

 Further more, Russian troops bombarded the largest nuclear plant in Ukraine, risking a potential radiation contamination of the region. 

Putin at the same time warning all other countries from involving themselves with the war, his air force violating the airspace of both Sweden and Japan. 

 If Russia is doing well in this invasion, does it need to branch out unnecessarily to instigate others? 

 If Russia already have the upper hand in the war, it would have ceased fire while the talk was on going, because it is not in a hurry to ask for peace. Putin would not be warning other countries from intervening and threaten to pull them into the conflict if he is confident of the situation. 

 I believe Putin under estimated his opponent, he expected the war to last only a few days and his opponent, being a "clown president" would have cowardly run into the safety of USA while he easily scoop Ukraine up. 

It never crosses his mind that this "clown president" managed to unit the country to fight the invasion and united the European Union to provide weapon support, strengthening Ukrainian's defense. He under estimated Ukrainian resilient against falling back into Soviet rule, so even when their country is weak and poor, they refuse to bow to the mighty Russia. 

 The Russian troop is ill prepared, they have not anticipated a prolong warfare and failed to ready sufficient resources. The financial sanction from the world also making it difficult for Russia support its troop with replenishment, considering the size of the troop that need to be fed. 

 What amazes me however is the shortage of fuel, considering Russia to be an oil producing country. Shouldn't this be one resource that Russia is not lacking, unless of course they do not have the refinery know how? 

What happen if Russia loses this war? 

 Dictatorship suppresses people's will by force, up-rising are normally dealt with using violence and brutality. This happens when the dictator maintain the support of his army and his support. Robert Mugabe is one such person. 

 What if a huge loss resulted in his army couple with the financial difficulty to the people as a result of this war? 

Nothing will happen, a weaker Putin will still be ruling Russia as long as people still have fear of further losses. There is however a threshold to this and if breached, making it no better between submitting and rebelling, over throwing the regime may be a reality. 

 Putin is fear of what will happen to him if Russia loses the war. The continuous escalation of attacks on Ukraine is a clear sign that he has no leverage so far to demand Ukraine to agree to some of his terms, let alone Ukraine's surrender. He wants very much at least some of his objectives to be met so that he can claim victory to his own people, so that even when the military strength of Russia is seen weaker in the future, he is still a strong and successful ruler of Russia in the eyes of his people. 

 The escalation of violence in Ukraine is in fact trying to apply pressure to Zelenskyy to bow to him, at least partially so to give him reason to retreat gloriously. He is  worried that the west will join in the war physically, this will cause the war to drag on and the longer it drags the more unfavorable to Putin's position in the country. 

 At this moment, the one person who wishes the war to be over the soonest is Putin, and he needs to be seen victorious.