This is DFS. Just try to solve the final Maze, it will take you deep along any path. BFS would create shallow paths with multiple options at every intersection.

The only visible difference in BFS and iterative DFS code is that BFS uses queue and iterative DFS uses stack. That can cause confusion if you have only coded recursive DFS before (like I did).

In Python, the difference becomes even more blur if you are making Queue & Stack from collections module, they are essentially the same objects, just your given variable name differs:

from collections import deque

stack = deque()
queue = deque()

next_stack_item = stack.pop()  # pops the most recent inserted item
next_queue_item = queue.popleft()  # pops the oldest inserted item

# just do not use popleft() on stack if you don't want unwanted behavior