Only a craftsman can determine the true reason for drafts. Therefore, it is necessary to contact the company that manufactured and installed windows.
So, what could be the reasons for drafts from metal-plastic windows? In most cases, this is an incorrectly adjusted fitting, which facilitates to depressurize the window structure. If you have settled in an apartment with already installed windows, check that the window is not in use in the winter weathering mode (these custom fittings could be installed on request of the customer).
Sometimes, in the absence of proper care, there are problems with a rubber sealant, which, losing elasticity, fades and breaks out. Replacing a seal in a latch is usually not a problem.
In addition, incorrect installation may also be the cause of the draft. In this case, only reinstalling windows can save the situation. In any case, it is not necessary to engage in independent activities, because only a craftsman can help with determination of the causes of the problem and its solution.