The registered hooks were removed before they are called. Try something like this:
    t_FM = []
    s_FM = []
    hooks = []

    def hook1(module1, input, output):
        print("hooker Working")
        t_FM.append(output)

    hooks.append(t_model.tbackbone.layer2[1].conv1.register_forward_hook(hook1))

    def hook2(module2, input, output):
        print("hooker Working")
        s_FM.append(output)

    hooks.append(s_model.sbackbone.layer2[1].conv1.register_forward_hook(hook2))

    your_model(input_tensors)  # forward with firing all the hooks registered
    for hook_handle in hooks:
        hook_handle.remove()

Also, you don’t need to set t_FM and s_FM as global (nonlocal) variables .