Nested list addition error

arr=[[0 for _ in range(n)]]*m

This is a sample code and the problem is that the nested list is not adding 1 to just l[0][0] its also adding it to l[1][0] and the answering being printed is [[1,0],[1,0]] instead of [[1,0],[0,0]]
I’ve tried this on a lot of compilers and it’s still giving the same answer idk why can someone help me with this.