Why is Aug 22 - 26 considered a concern for the Ukraine/Russia war?

🆕🔥🔥🔥Huge traffic jam on the exit from Kiev.
Many are simply afraid of what could happen from August 22 to 26🔥🔥🔥 pic.twitter.com/eT9yIrjFvu

— 🇷🇺The man who saved the world🇷🇺 (@ILRUSSO1) August 21, 2022

I keep seeing these dates. Apparently people are worried about it. WHY!!!???