I have read that the Ukrainians increased the flow of water into the reservoir, raising the water level from 14m to 17m. Could that have had an effect?

This is from CNN:

The critical Nova Kakhovka dam in southern Ukraine was damaged just days before suffering a major structural collapse in the late evening of Monday or early hours of Tuesday, a CNN analysis reveals.

CNN cannot independently verify whether the damage to the road bridge played a part in the dam’s collapse, or whether it was destroyed in a deliberate attack by one of the warring parties.

Satellite imagery from Maxar shows the road bridge that ran across the dam was intact on May 28, but imagery from June 5 shows a section of the same bridge missing. Analysis of lower resolution satellite imagery suggests the loss of the bridge section took place between June 1 and 2.

Some background: Meanwhile, data shows water levels in the reservoir behind the dam were at record highs last month, according to the Hydroweb information service. Levels had plummeted earlier in the year, the same data shows, prompting Ukrainian officials in February to warn of possible shortages in drinking water supplies, and water for agricultural use.