I am running a 2012 MacMini, and recently installed an SSD to replace the spinning HD it came with. After partitioning to 2, I CarbonCopyCloned the Mojave OS to one partition, and an installation of Yosemite on the other.
Now I notice that the Mojave drive is MacOS Extended, not APFS. The question - can I leave it like this, or will i run into issues? If this situation is bad, I can boot Mojave from an external drive and reformat that partition. Just asking if this is necessary.