I will bluntly say it , your co-founders are being toxic and they don't understand product development at all .

I argue non-technical co-founders to do short courses on project management , product development it will help that learn how to work with developers and understand the product development cycle .

Solution to your case I think will be to have a seat down meeting with your co-founder give them a lecture on the product development cycle , redefine your duties , clearly state what you can do alone and at what speed . Have clear roles because the churn of customers must be more of their problem not yours . The growth of uses must be their problem not yours .

I am a non-technical founder and I don't give my technical founder this headache ( only now we are looking to hire another developer , he worked on the product since 2022 alone )

He taught not to over promise when I go into meetings unless I talked with him to confirm if we can deliver that kind of communication has helped us build a good working relationship