Since macOS Sequoia 15.x (currently on 15.0.1) USBClean 4 does not hide itself after startup at login. The configuration to do so is ticked (both "open USBClean at login" and "and hide" are ticked). So are "show in menu bar" and "hide dock icon".

It's annoying because every boot/login I now have to close the USBClean window.