During tonight's gaming of War Thunder I managed to knock out a M4 Sherman with the P.7.T AA mobile heave machine gun. In general it is hard to knock out tanks with AA weapons which are 25 mm or below - the P.7.T has four 13,2 mm heavy machine guns.
There were two main reasons for why it was possible to knock out the Sherman tank:
Sherman player managed to kill two members of P.7.T crew - driver + co-driver. However, machine gun fire from the Sherman did not hit my gunner (marked by the red square)
When I was aiming towards the Sherman I focused on the "weak spots" on the turret such as observation prisms, periscope and holes since it was the only chance to get bullets into Sherman and in order to produce friction.
Btw, here is how a Sherman prism looks
Source: https://www.worthpoint.com/worthopedia/periscope-m6-spare-prism-m4-sherman-1794042400
Thanks for reading and keep on gaming :)