tl;dr: A Google Workspace Business Plus admin reported seeing warnings in Firefox urging them to switch to Chrome to "secure your device," served from access.workspace.google.com/remediate. Google support clarified the prompts only target admins accessing admin.google.com and are "recommendations" rather than blocks, but said this won't be documented publicly. The author is concerned about Google nudging users away from Firefox despite officially listing it as a supported browser.