Android 10 Fastboot not detected AB boot slot

fastboot set active slot
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zip package flashall: Flash all partitions from $ANDROID_PRODUCT_OUT On AB devices, flashed slot is set as active Secondary images may be

try setting the slots again, without the space between -- It will return fastboot --set-active:a fastboot: unknown option – set-active:a

fastboot change slot But i cant uninstall those modules without twrp So i decided to flash twrp into a boot slot via fastboot then, i set the active-slot to that but then I still

fastboot set active slot slots ourselves using a Fastboot command Changing Android's Active Partition Slot