You should probably remove all partitions, and start with a fresh slate.
To use UEFI booting, the disk should have a GUID Partition Table (GPT) which allows greater than four partitions to be created (if I recall correctly, the functional limit was 128 partitions).
You can use GParted (GUI) in the Live Manjaro environment to clear the disk and create a GPT partition scheme. Then, you can reboot and install the OS.
The medium used to install an OS must also have a GPT partitioning scheme, and must boot as UEFI. For example, if you use Rufus to create a Manjaro Installer, you must pay attention to the Rufus configuration.
I personally recommend creating a Ventoy USB - See the link I gave earlier for a functional guide to using it correctly.
Most USB drives/thumb dives are likely prepared as BIOS/MBR disks – you don’t want this → not for a USB → not for a HDD → not for an SSD.
When preparing your system via Calamares it will show you (near the top of the screen) whether the disk you are installing to is MBR or GPT - it should be GPT for UEFI booting. Pay careful attention.