Smoke Purifier Leakage

Since 2 Weeks i own a XTool smoke purifier. So far the unit works more or less as expected. BUT there is one thing that is driving me crazy. If i crank up the fan speed of the purifier it sucks air on the sides of the top lid. Did anyone else notice this kind of problem? How can this be solved properly? I tried already Window sealing foam stripes but it seems to not help at all.