Number of Islands problem on leetcode - incorrect answer on leetcode but correct locally

Question

I am trying this solution for the number of islands problem on leetcode.

class Solution:
islands = 0
visited = []
def numIslands(self, grid: list[list[str]]) -> int:
    self.islands = 0
    islands = [  ]
    _grid = [ row[:] for row in grid ]
    for r, row in enumerate(grid):
        for c, col in enumerate(row):
            if grid[r][c] == "1":
                islands.append( (r, c) )
    for island in islands:
        self.dfs(_grid, island, ignore=True)
            
    return self.islands

def dfs(self, grid: list[list[str]], island, ignore=False):
    if island in self.visited: return 
    row, col = island

    if ignore and grid[row][col] == "1": 
        self.islands += 1
        print("incrementing")
    if grid[row][col] == "1":
        if not ignore: 
            grid[row][col] = "0"

        print((row,col), "ignore = ", ignore)
        self.visited.append((row,col))
    
        if row + 1 < len(grid):
            self.dfs(grid, (row+1, col))
        if col + 1 < len(grid[0]):
            self.dfs(grid, (row, col+1))
        if row -1 >= 0:
            self.dfs(grid, (row -1,col))
        if col - 1 >= 0:
            self.dfs(grid, (row, col-1))
            

When I run it locally(m1 mac python version 3.9.10) on the test input:

grid = [
 ["1","1","0","0","0"],
 ["1","1","0","0","0"],
 ["0","0","1","0","0"],
 ["0","0","0","1","1"]
 ]

I get the correct number of islands(3), whereas, in leetcode, it says that my solution only returns 2 as the number of islands.

I don't know what maybe causing this issue, and i thought it had something to do with inplace modification of the grid but that doesn't seem to be the case either since i made a deep copy of the original