Actually they have deposite centre where one can deposit his/her belongings before going in the Masjid but few people keep it there. Usually peoples don’t pick slippers of others. The cleaner removes all slipper which placed before the entrance and drag them to place where all shoes/slipper should be placed. That is how we miss our slippers/shoes.
Khair Mubarak
Ameen. Khair Mubarak
Almighty Allah hum sb ko Umrah or Hajj ki sa’aadat naseeb farmay. Ameen.