UPDATE 23/3/21: In a statement to Eurogamer this morning, Microsoft has explained the recent branding change for its underlying online infrastructure. In short, the new Xbox network phrasing is more "descriptive", the company said, and none of the systems, subscriptions or anything else you actually use were changing.
"Xbox Live isn't going away," Microsoft told Eurogamer. "We are making ongoing adjustments to create a simpler, more descriptive messaging system for Xbox in different areas. None of these experiences or features will change as part of these updates."
ORIGINAL STORY 22/3/21: Microsoft is renaming Xbox Live, its underlying online multiplayer and digital media delivery service, to 'Xbox network', a move it says will help distinguish it from Xbox Live Gold.