add to app/models.py

models.py

class User(UserMixin, db.Model):
	... 	

	@staticmethod
    def validate_reset_password_token(token: str, user_id: int):
        user = db.session.get(User, user_id)

        if user is None:
            return None

        serializer = URLSafeTimedSerializer(current_app.config["SECRET_KEY"])
        try:
            token_user_email = serializer.loads(
                token,
                max_age=current_app.config["RESET_PASS_TOKEN_MAX_AGE"],
                salt=user.password_hash,
            )
        except (BadSignature, SignatureExpired):
            return None

        if token_user_email != user.email:
            return None

        return user