Recreational drone pilots, why does the drone lose controller signal?

Today I lost my DJI Mimi 3 drone over water while trying to capture canoe races. Too bad as I think I videoed some spectacular paddling action. Also too bad because it’ll cost $450 to replace the drone and batter.

The drone was well in controller range 572 meters away and 28 meters high. Drone lost signal in just 4 minutes after launch. Drone had 3 bars (out of 4) of power at launch (equivalent to about 20 minutes of flight time). Controller also had 3 bars (out of 4) of power.

Suddenly for no apparent reason my controller verbally announced “signal lost” and immediately stated, “landing”. I hit “return home” but of course that didn’t work because the connection was lost. Drone landed in the water and quickly sank out of sight.

In the past I’ve flown that drone 2.06 kilometers away at 101 meters high with a flight time of 14 minutes with no problem.

The drone and its controller are fairly new (only a couple months old and never crashed or dropped).

What do you think?
Is there something that I could have done when the controller lost signal?
Has this happened to you?