and may have around 5,000 Russians still stuck in it.
General Putin's stubborn no-retreat strategy strikes again. He has no other setting. You can tell it is his instruction and that he doesn't care if the Russians in Lyman die. So instead of withdrawing 5,000 men whom he can use at a later date, he's lost them.
The key strategy for Ukraine is to find ways such as this to defeat the Russian army, knowing they are being led by a person whose decisions are predictable. If retreat is not an option, repeat Lyman over and over. They have a similar thing going on around Kherson, in which another larger Russian army is stuck because General Putin wouldn't let them withdraw.