Ha, I had never heard of this effect despite having studied Kamiokande (well neutrinos, at least) as part of a mini-dissertation for my B.Sc.

However, looking for sources relating to leaching by ultra pure water (UPW) not much turned up.

I did however find on Google Scholar a paper "Ultrapure Water: friend or foe?"... which lead me to https://www.balazs.com/sites/balazs/files/2023-03/pub0039-up... . Reading between the lines, Marjorie Balazs appears to have made a career out of UPW; she says in that paper:

"The ability for UPW to absorb and dissolve or react with all kinds of materials complicates other aspects concerning its use in the processing of wafers."

Seems like UPW dissolves anything, so lends credence to the anecdote.

Interesting topic, hadn't thought about UPW for wafer fabrication before.

Reminds me of the scene in Kung Panda 1 where one feather of the goose, Peng, falls into the tunnel which Tai Lung uses to unlock his cage and escape.

Isn’t that also the one where a sensor imploded and caused a chain reaction that destroyed like a third of the other sensors?

You aren't finding anything because it is not true. Ultra pure water does not become some kind of solvent.

It's the reverse problem: because the water is so pure it easily gets contaminated by minor things. So all the equipment has to be carefully cleaned.