Append only adding the same list again and again

[viraj1123]

Hi, I'm facing this really weird issue.I've been appending different lists to my list but while i print the result it shows that the last value appended is only added as many times as I appended different lists. My code and output will clear out exactly what I meant.
Here is my code:

def generate_MagicSquare(n):
    mat=[[0 for i in range(n)]for i in range(n)]
    i,j=n//2,n-1
    mat[i][j]=1
    number_inserted=1
    a=n**2
    while number_inserted<a:
        i,j=i-1,j+1
        if i==-1 and j==n:
            i,j=0,n-2
        elif i==-1 or j==n:
            if i==-1:
                i=n-1
            if j==n:
                j=0
        else:
            pass
        if mat[i][j]!=0:
            j-=2
            i+=1
        number_inserted+=1
        mat[i][j]=number_inserted
    return mat

def rotate_Clockwise_90(B):
    n1=len(B[0])
    for i in range(n1//2):
        for j in range(i,n1-i-1):
            temp=B[i][j]
            B[i][j]=B[n1-1-j][i]
            B[n1-1-j][i]=B[n1-1-i][n1-1-j]
            B[n1-1-i][n1-1-j]=B[j][n1-1-i]
            B[j][n1-1-i]=temp
    return B

x=[]
mat=generate_MagicSquare(3)
print(mat)
x.append(mat)
print(x)
a=rotate_Clockwise_90(mat)
print(a)
x.append(a)
print(x)
b=rotate_Clockwise_90(a) #Rotate by 180
print(b)
x.append(b)
print(x)

Output:

Output:
[[2, 7, 6], [9, 5, 1], [4, 3, 8]]
[[[2, 7, 6], [9, 5, 1], [4, 3, 8]]]
[[4, 9, 2], [3, 5, 7], [8, 1, 6]]
[[[4, 9, 2], [3, 5, 7], [8, 1, 6]], [[4, 9, 2], [3, 5, 7], [8, 1, 6]]]
[[8, 3, 4], [1, 5, 9], [6, 7, 2]]
[[[8, 3, 4], [1, 5, 9], [6, 7, 2]], [[8, 3, 4], [1, 5, 9], [6, 7, 2]], [[8, 3, 4], [1, 5, 9], [6, 7, 2]]]

Process finished with exit code 0

I think it has something to do with memory addresses, but don't have a good idea about it.
Any suggestions will be very helpful.
Thank you!