Self-doubt is just as human as fear, anxiety, or loneliness. It helps when there's some social environment that helps counteract these bouts. By the same token, if the existing environment works to enforce these demotivating feelings, then one needs to acknowledge that it maybe "them", not you, and either build some mental defences or just move on.

Everyone one on the team should be allowed to make mistakes or take bad choices. Juniors, seniors, managers... we are all people, we're all engineers, we're a team! Cult of perfection is limiting to everyone. The manager's job is to recognize everyone's contribution, no matter how small.

Too often, the teams project a higher bar than is actually reachable. Sure it will lead to sense of inadequacy, for absolutely baseless reasons.