Are computer programs able to do things for "no reason"?
That seems unlikely.
Is it possible that your account was suspended for:
a) a reason that you don't yet understand or know about
b) a reason that you don't agree with
Note that when Upwork suspends a freelancer's account, they provide information about what to do next to remove the suspension. You need to find that message. Look in email, spam mail box, under the bell icon, under the question mark icon, in your help desk tickets section, on profile editing page, etc.