First of all, these are coagulated proteins (albumin, myoglobin), which come out of meat or poultry when heated. There are also fat particles and some impurities (for example, blood residues), which give the foam a gray or brown tint.
Can there be antibiotics in meat and poultry
Manufacturers are required to adhere to conditions under which the product does not contain antibiotics or their residual amount is at a safe level and does not affect human health. Otherwise, the product will simply not pass veterinary control. That is, there may be antibiotic residues in a chicken bought from a store, but their amount is so small that it does not pose a significant risk to human health directly when consumed.
But there is a problem with the potential development of antibiotic resistance if you regularly buy meat from producers who did not comply with standards and had no control. For example, from private individuals. At the moment, there is no scientific evidence that the foam contains harmful substances and it should be removed for safety.