For this border crisis, Poles extend a warm welcome, unlike last time.

In Wroclaw, they are hosted by Robert and Hana Reisigová-Kielawski, an English language university instructor and a human-resources supervisor, who live with their two children. The couple didn’t have a spare room in the apartment so they moved their 5-year-old daughter to their bedroom.

“As we waited for their arrival, we got nervous,” Mr. Reisigová-Kielawski said. “We had no idea what physical and emotional state they would be in. I wondered how we should behave in order to be as helpful as possible, but also not overwhelm them. Which issues should we discuss and which are best left unsaid?”

One thing was clear from the beginning: They wouldn’t ask their guests how long they were planning to stay. Their invitation didn’t have an expiration date.

But whenever they asked if Ms. Fedchyk needed anything, she would say, “No, thank you. We’re just here for a few days.” As the invasion unfolded, however, it became evident that those days could turn into weeks, perhaps longer.

Since the war began, Ukrainians on both sides of the border have faced uncertainty. In Poland, the government is preparing an emergency bill that will make it easier for Ukrainians to access the labor market and some of the social benefits available to permanent residents.

Commentators have pointed out that the warm welcome Ukrainian refugees have received stands in stark contrast to the public response to the humanitarian crisis at the border with Belarus, which peaked in October. The government did not open the border to those refugees, most from the Middle East, and it banned aid workers from the border region — policies widely supported by Poles.

The Reisigová-Kielawskis, long active in various refugee-support programs, were frustrated.

“During that crisis the government made it extremely difficult for Poles to help refugees, and unfortunately many people chose to look away,” Mr. Reisigová-Kielawski said, adding. “The grassroots movement to help Ukrainians, which we are seeing at the moment, is immense and heartwarming, but I have the impression that it is also lined with a sense of guilt that as a society we didn’t do enough back then.”