Windows 11 randomly decides to rearrange my Start menu every other day

You want a Start layout that survives reboots, and the returning apps plus disappearing groups indicate that something is reapplying or losing the per-user layout. On a managed device, a Configure Start Pins policy, provisioning package, or Intune profile can overwrite user changes during policy refresh. Check Settings, Accounts, Access work or school, and ask the administrator whether a full or partial Start layout is assigned. On an unmanaged PC, install Windows updates, arrange only a few test pins, then sign out and back in. If they reset again, test a new local user profile; a stable new profile points to corruption in the original profile. Run DISM followed by SFC before considering profile migration. Avoid registry cleaners and scripts that delete the Start database. If both profiles fail with no management policy, perform a clean boot and submit Feedback Hub diagnostics with the Windows build and exact reset time.