From "The Analyst":

AVDIVKA UPDATE

Russian forces in the south west salient they created have effectively been cut off as Ukraine has regained the key fortified area of the restaurant services area.
Russia tried to send a column to reinforce their troops in Avdivka’s lower streets, but this was annihilated.
The Russians used a 2km waste water service pipe to get behind the restaurant and into south Avdivka. It’s very narrow and they had to crawl through it, so supplying and reinforcing the now cut off island they’re in in south Avdivka is near impossible, if not pointless.
The tunnel needs to be destroyed at both ends and it’s deep so this hasn’t yet happened.
Eradicating the Russians in the housing they occupied is well underway.
Overall the Russian operation was quite imaginative and it gave them a major gain - taking the southern defences completely and the Ukrainians by surprise. In some ways the Ukrainians should have expected use of the tunnel, or at least taken precautions to block it. It’s far more likely they just never expected it could be used if they even remembered it was there.
Russian success - and it was, there’s no getting away from that, it was a daring and imaginative operation, was simply not followed up. Senior commanders doubted its likely success and no one was ready to exploit it until it was far too late. By then the Ukrainians had snatched back the restaurant’s fortification, because nobody reinforced the Russian forces, and now the few remaining Russian troops are more or less trapped, and the whole thing has turned into a Russian disaster. It’s not something Ukraine will fall for again and they’re probably looking to make sure nothing like happens anywhere else either.
This could have been the most consequential move the Russians made in months.
If they had been ready to exploit the success and acted quickly, given it the support it needed, they could have surrounded Zenit and have broken deep into Avdivka. It would in all likelihood have been the beginning of a much faster end for the town which would have quickly become untenable.
Instead their own handful of competent people were as usual, let down by hide bound commanders with zero imagination. Ukraine has always worked well against such opponents and did so again. That they were just as quick to see what had happened and responded with lightning pace to retake the initiative says it all.
Yet another bad day for Russia!

Slava Ukraini 🇺🇦!