Drowning is when a living organism is submerged, flooding is when buildings are submerged.
...and dies from it, which is a pretty important aspect to the word. If the organism doesn't die, it's swimming or just submerged.
Ie: The Bering Strait land bridge flooded 10,000+ years a gap and it’s still under water. https://en.wikipedia.org/wiki/Beringia
Ultimately sea level rise is a temporary thing. Given enough time the oceans will boil as the sun ages unless something drastic changes.
Drowning is when a living organism is submerged, flooding is when buildings are submerged.