Is the Apple Watch Having Water Issues?

Two weeks ago, we had my son’s 4th birthday party at his swim school. While there, I noticed my Apple Watch had a terribly low battery, and eventually died. When we arrived home, I tried charging it, on multiple chargers for hours. But it never came back to life.
It was an Apple Watch Series 7, which will lose support later this fall, and I was already planning on replacing it with something else around that time. So, I decided to upgrade 3 months early, and ordered a Garmin Instinct 3 - Solar (45mm). Frustrating, but fine. It was an older Apple Watch after all, and I’m much happier with my Garmin (I literally used the ‘torch’ light to find a superhero mask for my son while writing this draft).
Fast-forward to this past weekend. We were visiting my in-laws for the US holiday, and spent some time dealing with the extremely hot (38C) weather by swimming. Nothing crazy, mostly just walking around the pool and swimming with our son.
That night… my wife’s Apple Watch (Series 10!) didn’t charge. When we got home, we tried to diagnose it, looking at logs, using different chargers, resetting it - nothing. It eventually lost its 1% charge and we made an appointment at the Apple Store. After sitting around for an hour while they tried to diagnose the problem, we were told that they were also unable to figure it out. To proceed, we would have to spend $300 to ship it offsite to maybe get it fixed. So we bought my wife a Series 11 instead. Frustrating, and this time, not fine. The watch is only 1.5 years old.
It should be noted that while at the Apple Store, there was another family sitting at our table experiencing the same problem with an Apple Watch SE after a weekend at the beach.
I’m sure there’s a low but persistent chance of this happening, but two watches in two weeks, after years of use? It makes me wonder if there’s a low-level firmware bug executing in water prevention code or something. Or not. Maybe I’m just a paranoid programmer. Regardless, this all sucks.