Just wondering why translations such as the NASB & NET (reputable translations in my opinion) translate the future verb ἔσται as a past tense in Mt. 18.18? I am thinking that the force of the indicative mood is why, but could be mistaken (be merciful to me

"Truly I say to you, whatever you bind on earth shall have been bound in heaven; and whatever you loose on earth shall have been loosed in heaven" (NASB).
Thank you much in advance.