However, if today Ukrainians think that they can conduct ruthless politics towards Poland
Of course they think they can.
Zelensky said "Macron has something wrong with his head, if he thinks it's important 'not to humiliate Russia'".
At the NATO summit in Vilnius he called Germany and America's hesitance to provide Ukraine with a path to NATO as "disgusting and absurd".
When Ben Wallace, British Minister of Defense, decided to show a little bit of irritation with Zelensky, he said the following: "Whether we like it or not, people want to see a bit of gratitude." Zelensky promptly reacted with this: "I just do not know what he means, how else we are supposed to express our gratitude. He can text me to explain it... We can wake up every morning and personally thank the minister."
So just because Poland is many times wealthier than Ukraine, and plays a much more important role in pretty much anything that matters, doesn't mean Ukraine has to respect you. They twist the arms of superpowers, not just Poland. Ukraine eats Poland-sized snacks for breakfast. It really is a turbo nation.
I just hope they don't find themselves in some uncomfortable situation at some point, due to insufficient tact in dealing with people. But so far - everything is working perfectly for them - and it's the rest of us that look like idiots.