However, Poland can still find ways to dissuade Ukrainian workers from heading west, the researchers said, based on a survey of several hundred refugees.
The study, entitled From Poland to Germany: New Trends in Ukrainian Refugee Migration, was carried out by the EWL Migration Platform and the University of Warsaw's Centre for East European Studies at the request of the Polish Prime Minister's Office.
According to Eurostat, the European Union's statistics agency, at the end of July, there were around 1.15 million Ukrainians registered in Germany, while in Poland the number was just over 971,000.
Since August last year, the number of registered refugees in Poland has decreased by more than 350,000, while in Germany it has increased by more than 410,000 during the same period, the study's authors said.
Their research shows that "having friends and acquaintances in Germany" was the key factor for refugees deciding to move from Poland to Germany. It was mentioned by 43 percent of those surveyed.
Meanwhile, 42 percent listed "more attractive social benefits" in Germany, and 38 percent mentioned "the possibility of accumulating more savings." Twenty-seven percent highlighted "job offers with higher pay."
The study authors said they surveyed a total of 400 Ukrainian citizens who came to Poland after the outbreak of the war and then left for Germany.
Russia invaded Ukraine in February last year, launching the largest military campaign in Europe since World War II.
Since February 24, 2022, when Russia invaded its neighbour, nearly 15.55 million people have crossed into Poland from Ukraine, according to the Polish Border Guard agency.
In March last year, Poland enacted a measure to offer wide-ranging support to Ukrainians escaping the Russian invasion of their country.
The measure grants them residence rights and ensures access to education, healthcare and social benefits.
Andrzej Korkus, CEO of the EWL Migration Platform, said: "After February 24, 2022, Germany responded to the influx of refugees from Ukraine by introducing the most liberal regulations on access of foreigners to the labour market, together with fast and often compulsory language and vocational courses, while taking advantage of the high level of professional qualifications of Ukrainian citizens at the same time."
He added: "These measures, combined with the acute shortage of labour on the German market, indicate the likelihood of a further strengthening of this migration trend."
Click on the audio player above to listen to a report by Radio Poland's Danuta Isler.