Propaganda.
" Propaganda."

Why?
3rd Tanks was not in the original Ukrainian OB. That is indeed a reserve formation.
I understand a lot of the reserve armor was in Kharkiv, and not immediately available for mobilization.
Ukraine fully mobilized its reserves at the time of the invasion nearly two months ago. Those units have been organizing and ramping up since then. In the meantime, they've also received a lot of weapons and equipment from members of NATO. So, it stands to reason that those reserve units would finish mobilization and head towards the front sooner or later.
Russia clearly has more potential manpower reserves than does Ukraine. However, Ukraine was invaded and so is basically an entire country at war, and Russia is not. No mass conscription, etc.. Nobody is disputing that. So unless Russia decides to do a much greater mass mobilization than they have yet committed to, the balance of forces will start tilting more towards Ukraine over time. It's just a matter of numbers/national commitment.
Maybe they can catch up with Zelensky’s mouth.