Then, by definition, it must already be fixed.
As mentioned aboove, the most likely is that SecureBoot needs to be disabled in BIOS; why it was magically re-enabled, is anyone’s guess, at this time.
However, there are other possibilities; poor Internet connection leading to a damaged ISO being downloaded; always check ISO’s for consistency; make sure checksums of ISOs match that of the downloadable .sha256 file.
Or; misconfiguration of the application used to create the Manjaro Installer; whether it be Rufus, Etcher (not generally recommended for Manjaro), or even Ventoy.
On the chance that the latter applies, the following link might be useful for creating a Ventoy USB properly. Remember that if installing as UEFI, the Installer USB must also boot as UEFI.
Regards.