Ah yes, that’s what I saw as well, misreporting the size of the different volumes.
Could either be just a visual bug, or a proper bug with the volume creation. Or maybe even it just doesn’t work like that.
Sorry can’t help you discern which it is, as I never did go through with installing it with btrfs. I see you have an unknown installation listed, probably means you are dualbooting with another Operating System as well? My initial suggestion was going to be “try and see if it works as you intendo to”, but it’s probably unsafe since you are running other OSes.
You could use the ext4 file system instead which is what I’m currently doing. Or file a bug report at https://bugzilla.redhat.com/ so fedora developers fix in for future releases (choosing Product Fedora and Component Anaconda). If you don’t want to, tell me, and I can do it.
Also, maybe someone else here can help?