It could be a typo, misremembered version number, or a repack from a forum (PSX-Place, PS2-Home, etc.) with:
Check your file: Look for a readme inside the download — it may actually be USBUtil 2.21 renamed. usbutil v21 ultimate for ps2 usb mode 2 link
Let us assume you have downloaded USBUtil v21 Ultimate from a safe "link." Here is your workflow: It could be a typo, misremembered version number,
Your USB drive is now prepared, but the PS2 USB Mode 2 Link feature must also be enabled in Open PS2 Loader. Check your file: Look for a readme inside
The central feature of USBUtil regarding "USB Mode 2" involves the fragmentation and file naming convention required for high-compatibility gaming.