I think this is because we detect the fact that it is netty only once Netty web requests are actually being processed. See this as additional information that is gathered then.
This does not change the identity or name of the process group, so it should not have negativ impact I hope.
Process type influences a lot of internal processing, like creation of Process Groups, so it is not possible to edit it. Please contact our PM team, if our automatic discovery of process type does not suit your needs.