Moving a subdomain and all of its content to a new URL

Hello. We`re looking to move a subdomain and all of its content to a new URL (that will no longer be a subdomain--help.website.com > website.atlassian.net/wiki). My question is how might this impact the main domain and its rankings/authority after the move? How can I go about researching potential impact on that and overall site visits just so we`re aware of the implications? Also, if there are any resources or suggestions for mitigation strategies that might help, that would be incredibly appreciated as well. Thank you in advance for any input!