What's wrong with my bron-kerbosch-algorithm

Question

I cannot get what do I miss in my code, mostly right, but in graph that is large enough, WA appeared. graph is a dict which stores input and looks like:

graph = {
    4: {5, 6, 7, 8, 9},
    5: {4, 7, 9},
    6: {4, 7},
    7: {4, 5, 8, 9},
    8: {4, 7, 9},
    9: {4, 5, 7, 8, 9}
}

graph = take_inputs()
cliques = {}
for i in range(3, max(graph)+1):
    cliques[i] = []
    
def bron_kerbosch_pivot(R, P, X, graph):
    if not P and not X:
        # Report R as a maximal clique
        cliques[len(R)].append(R)
        return
    
    for v in P - graph[(P|X).pop()]:
        bron_kerbosch_pivot(R | {v}, P & graph[v], X & graph[v], graph)

        P.remove(v)
        X.add(v)

def print_clique(cliques):
    for length in cliques:
        if not cliques[length]:
            return
        
        group = sorted(cliques[length], key=lambda x:sorted(x))
        print(length)
        print('\n'.join(map(lambda clique:('{' + ','.join(map(str, sorted(clique))) + '}'), group)))
            
bron_kerbosch_pivot(set(), set(graph), set(), graph)
print_clique(cliques)

It is my expected input, nothing wrong when input is that small

3
{4,6,7}
4
{4,5,7,9}
{4,7,8,9}