Hey, I saw your feedback through the bot as well.
I'm honestly not 100% sure what the issue is here as inputting bank pins is automatically done on Runemate's end, not in my bot, as my bot doesn't have access to account bank pins (or any other account info). So this sounds like something the Runemate client developers would need to fix on their end. That being said, I'll mention it to them. You can also mention it on the Runemate discord.
I don't know when it'll be fixed though; Could you change your pin setting to a slightly looser one, maybe? I don't use bank pins, but I think there's an option for only needing a pin once per IP per 24 hours or something like that? Not certain if that would help.
PS if you're using Runelite please try using the vanilla client, as Runelite support still has some bugs.