Alwasy check the ISO before writing to USB using shasum eller gpg.
The utility you choose to write the image to USB must support dd-mode.
The only exception is ventoy - as this is a simply drag’n’drop operation to the prepared stick.
However - using ventoy - you have two grub loader options. Sometimes the first work sometimes the other.
Some image applications - unetbootin and rufus, perhaps others as well - is unpacking the files and tries to boot the image - that will not work with Manjaro ISO.