Disable "power modification" from moderator group to a specific group

Hello,

i'm a bit lost with the settings of that specific permission. I created a new group called "bot" which is almost equivalent to "server guest".
I've also a "moderator server" group and i don't want them to be able able to modify the power of that specific group, the "bot". Unfortunately they're still able to do so. They can't remove this group but they can add others groups on top of this.

This is how my permissions are set:

moderator :
i_group_modify_power disabled
i_group_needed_modify_power 75
i_group_member_add_power 60
i_group_needed_member_add_power 75
i_group_member_remove_power 60
i_group_needed_member_remove_power 75
i_permission_modify_power 60
b_permission_modify_power_ignore disabled

bot :
i_group_modify_power disabled
i_group_needed_modify_power 75
i_group_member_add_power disabled
i_group_needed_member_add_power 75
i_group_member_remove_power disabled
i_group_needed_member_remove_power 75
i_permission_modify_power disabled
b_permission_modify_power_ignore disabled

I don't understand why, even with "needed power" set to 75, they're still able to add and accumulate other groups to that group (like server member). By the way, i don't want to give any power to that bot.
Any help would be very apreciated,thank you.

Disable "power modification" from moderator group to a specific group