I agree with Alessio - this complicates teraforming. Just because it causes problems with one type of flower farm shouldn't be enough reason to change the behavior. Effectively, flooding an area causes a "reverse spread" of grass and mycelium using random tick behavior. If the water was removed, the area would fill in again. This is a realistic and predictable expectation. Without this function, removing mycelium would require digging and replacing, covering and then removing every block.
But the fix for it decaying too quickly is to make it not decay at all? As the last comment in the referenced ticket states, it means mycelium is impossible to teraform. (Which was tough to begin with as it spreads faster than grass, skips blocks and can spread in the dark, which means careful water management to accomplish) This leaves literally placing solid blocks over the entire surface or digging and replacing as the only alternatives.
Honestly, slow decay seems more realistic when you flood an area, and in the case of a flower farm, the grass will return if given time.
Oh no - you're saying this is the expected behavior!?
Since several other opened bugs have been marked duplicate and closed, I'm posting here. This is happening repeatedly in 1.14.4 when exiting a boat on ice in the nether. The player also behaves "trapped" as though stuck - movement is very slow and returns to normal after getting out of that block. Boat reappears upon relogin. Also, I don't know if it's related, but when breaking ice, occasionally an ice block is removed, but water flows around it like it's still there. If you stand in that spot, you get "stuck" as described above. It's solved by placing an ice block and breaking it again.
Have also repeated experienced this, primarily in the nether - dismount, horse (or mule) disappears but can still hear it. Present after exiting and reentering the world (too chicken to leave and reenter render distance). Windows 8, Java 11, MC 1.4.3, no mods, both single player and multi.
This also occurs if the beacon has water above it.