I suppose it all depends on what you consider to be a major breakthrough.
Russia has lost a third of their initial gains. They are now advancing along about a 100 miles of the frontline, at a rate of about a mile every month. At that rate, it will take several million years for them to win the war. They have all but given up at trying to push back Ukraine's beachheads on the left side of the Dnieper River.
Russia did finally get back most of their own territory from Ukraine, but it took 7 months. And Ukraine still has some Russian territory, which the Russians have now decided just to surrender to them.
What I -have- noticed is that, with a minor blip near the start of the war, they've been taking territory from Ukraine at a pretty good clip.
Russia had a huge success at the beginning of the war. That was followed by Ukraine having huge successes of seizing back a third of the territory. There was then a stalemate. Ukraine could not cross the minefields, and Russia could not cross the river. Ukrainian positions on the north and south are extremely solid, so there is only about 100 miles in the center of the line where Russians can advance. They are using human wave attacks to advance slowly there.
Then about 7 months ago, Ukrainians advanced in Russia seizing ten times as much territory as the Russians have been able to get in Ukraine in the last 2 years. Russia was given a choice, either give up their tiny offensive, or surrender their territory. Putin decided to keep up the offensive, and to ignore the seizure of Russian territory for a few months. He then looked for whoever he could find to retake the Russian territory, including North Korean mercenaries.
Putin has taken back most of the Russian territory taken, and is regularly seizing about 25 to 50 square miles of Ukraine a month. Ukraine is giving up territory to save lives.
I suspect that much of this "third" had not been meant as a permanent capture. Could you specify what land you are speaking of?
The Kharkiv counteroffensive captured the entire northern frontline. The Kherson counteroffensive captured all of Mykolaiv, and a major chunk of Kherson. Kherson is one of the "Four Donbas Provinces", and the capital city of Kherson is the biggest city in the Kherson Oblast. According to Putin, it is part of Russia now.
These offensives meant that Putin had lost the second biggest city in Ukraine, Kharkiv, and had lost all hope of seizing the third biggest city in Ukraine, Odesa. Had he been able to capture Odesa, then Ukraine would be landlocked, and have an absolutely huge, undefendable frontline to defend just south of their capital city Kyiv.