Ahsan Allahu ilaykum, I arrived late to the salah so I prayed with another brother who arrived late, I didn't realize but we were praying with a wall behind me so when I went to raku3 my feet moved slightly in front of his even though he is imam. Is there any issue in this? Barak Allahu feekum.

Ustadh AbdulAziz al-Haqqan

I think the issue here is waswas and that is the important matter that should be tackled.