There are many reasons why the Portuguese consulate can deny your digital nomad visa application. One of the significant reasons is when an applicant does not meet the minimum income requirement. Due to this, it is advisable to surpass the minimum requirement.
Another reason why your application may be rejected is because there were discrepancies between the details on your application form and your ID card or passport. Lastly, it could also be that you did not provide all the supporting documents the consulate needs to make a decision on your visa application.