Observing this issue for quite a few versions. Can confirm this is still present in 1.19.4.
I have the same issue on Nintendo Switch and Windows 10 Edition. Not always but often if you distiguish water source blocks with other solid blocks there is a quarter of a full block of water flowing left behind and it stays flooding. Never had this in other previous versions, only in the actual up-to-date-version.
Can confirm still in 23w14a
[media]Thanks @octojen for the work-around via NBTExplorer. Simple, easy and working!