If everybody left, it looks like dispersing before an incoming attack.
If they went on a mission of some sort, it would seem unlikely that they would all go. Not every ship is suitable for every task.
I think a Naval attack on Odessa would be a high casualty exercise for the Russians, with little prospect of being to hold anything or meaningfully follow up.
The evacuees:
2 Vasily Byko type patrol boats, 2 Buyan-M type missile launchers, 2 Ropuchas, 1 Ivan Gren type landing ship and another Tapir type and 2 Kilo class submarines