Recognise a different data location before repairing the library
Suppose a second Windows Kodi installation suddenly shows the usual household library instead of the small collection prepared for testing. First check which shortcut launched it. The portable-mode manual explains that the launch argument selects portable behaviour; placing another executable in a different folder alone is insufficient. An apparently missing test library may therefore be a different active data location rather than deleted media.
Follow the portable installation requirements
Kodi documents choosing a separate installation location writable by the ordinary user and adding -p after the executable path in the shortcut target. It also calls out the Start-menu shortcut if that entry will be used. The resulting portable_data directory belongs to that installation. The standard installation and a shortcut without the argument can use a different data arrangement, so record which entry you intend to keep using.
Verify the selected instance with a harmless setting
Use a distinctive, non-sensitive interface setting or a small known library item to confirm the expected installation. Keep the current data backed up before testing another release, and do not label portable mode a security sandbox. The manual also gives different macOS caveats and does not offer portable installation on every platform. Its v22 note about simultaneous portable instances is version-specific; it is not a reason to assume that several older builds can run together identically.
Questions, answered
Does installing Kodi in another folder automatically enable portable mode?
No. The documented Windows workflow depends on launching it with the portable argument and using the intended writable data location.