assalamu alaikum wa rahmatullahi wa barakatuh, the imam at the masjid thats near to me uses a mat for his feet and i dont know if he reaches the ground while in sujud, its thicker than the mat of the followers. what should i do as i dont want that my prayers are invalid?

Ustadh AbdulAziz al-Haqqan

It seems like u might be suffering from severe waswas, and that is the problem that really should be addressed, as for the imam he is standing on the ground akhi even if his mat was thicker than yours. The salah is valid in sha'a Allah.