I am a UX designer

Few designers think they can understand the problem better than the stakeholders, better than the team, and sometimes even better than the users. This completely leads to the situation where designers are satisfied with their solutions and avoid criticism.

Regardless of how long you've been in the business, all your ideas are just hypotheses. You have to validate the hypotheses. If you skip the validation step, you are basing your work on invalid hypotheses. Note that as a professional experience designer, instead of emphasizing your assumptions and presuppositions, focus on your users, end product users, and product stakeholders.