Looks like Russians pinned a bunch of Ukrainian forces around Chasov Yar after the Avdeevka breakthrough. This is a critical problem for Ukraine because there aren't any fortification in depth, so losing these strongholds means Russia would be easily able to advance all the way to Dnepr. As a result, Ukraine threw their best brigades to try and slow down Russian advance at all costs. Now it looks like Russia is opening up a second front from the north, and we'll see if Ukraine has the resources to fight on both fronts or whether they'll be forced to sacrifice one to try and hold the other. Of course, if Russia makes a major breakthrough in either area then it's likely that the whole front is going to start collapsing anyways. The next few weeks might be a pivotal moment in the war.
Yes, apparently they're stretching the front so far that the Ukronazi defenses are being breached in multiple places and they can't hold them because they're missing manpower. I've also heard that there is a large gathering of troops in Bryansk and Kursk near Sumy and Chernihiv Oblasts so it's possible that there are plans to stretch the front a the across the whole border. Ukronazis are already pushed 4km in Kharkiv. Tonight is going to be a big night considering that offensive will be in full speed in Kharkiv.
It's probably worth waiting a few days to see how this develops, but definitely looks that it could be significant. Russian approach has been generally very cautious, so they might just be probing right now. However, if Ukraine is really as short on manpower and ammunition as they appear to be, then Russia might start a serious offensive.