1. If both your feet are above the ground in Sajdah for the duration of ?three Tasbeehs?, then the Salaat is invalid. If only one foot is on the ground, the Salaat will be valid, but Makrooh. (Shaami vol.1 pg.449)
2. If only one foot touches the ground in the standing position, it would be Makrooh. However, the Salaat is valid. (Hindiyah vol.1 pg.68)
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai