Poland is not happy about deeper integration between Belarus and Russia. Poland still hopes to become the leader of New Europe. It follows the concept which puts forward the idea of Polish Prometheus, sympathising with all those willing to fight Russia.
Summary
G7 positions are based on the recognition of US global dominance. Canada and Italy do not have enough weight. US occupational military forces have remained in the territories of Japan and Germany since WWII. Both countries are not fully sovereign. UK and France have a very narrow avenue for taking international decisions beyond the US’s position. Hence, the G7 turned into a group of Soviet-like bureaucrats led by Washington. It has not much to discuss beyond European, American, or Japanese problems. Hence, Trump’s statement to bring Russia back, as discussions about Ukraine, Syria, Iran, North Korea, Venezuela, Saudi Arabia, or global energy security are senseless without Moscow.
Disproof
Recurring pro-Kremlin disinformation narratives about Western countries, Germany and Japan in particular, as US vassal states. See other examples of cases presenting different countries under the thumb of the Americans here.
Japan is a fully sovereign state recognised by the international community. US military presence in Japan is regulated by the 1954 Mutual Defence Assistance Agreement. The Constitution of Japan forbids the formation of traditional military force. Read more by the Council of Foreign Relations.
Germany is an independent and sovereign country and is not dependent on the United States of America in terms of foreign policymaking and therefore it is a conspiracy theory presented without any evidence. Germany and the US have close partner relations of two sovereign and independent countries.
For other disinformation cases see: Japan is not fully sovereign, Germany is a vassal of the US; Germany is the executor of US hegemony over Europe; The USA is controlling Europe through occupied Germany.