New filesystems

Hello,

I have read that as of version 13 the new filesystem is “EROFS”.
Does this change also happen to existing installations? Or do we need to do a eMMC/SSD format and do a clean install?

Also as of version 13.1 it added exFAT and NTFS, same question here. And how can we choose what file system we like to use?

Last question about this, which is now the preferred file system for HA OS? And does this apply to the whole installation or for example only to the (in my case of HA Yellow) to the eMMC and not the data disk SSD.