That means either the Russian forces would soon close the loop, trapping the 200 thousand AFU troops inside before pummelling them with large-yield munitions like the FOAB, missile strikes, carpet bombings, long-range artillery barragess, or any combination of these bombardment methods;
Or that if the Ukrainian General Staff has ordered those 200 thousand AFU troops to immediately evacuate the loop after confirming the MI6 intel, causing their hasty retreat and creating traffic jams on the very few roadways that leads from Severodonetsk to the west. The Russian forces would then proceed to bombard those few roadways that are stuck with many thousands of AFU troops with artillery barrages, missile strikes and bombing runs.
And compared to the first option where those AFU troops could just shelter in buildings across the city, the second option of being on the move would render them out in the open and exposed to Russian firepower.
If the later is true, then we may be seeing the Ukrainian version of the Highway of Death...