Has anyone else experienced water resistant problems with Garmin 6S Pro?

So... Your wife's watch is more than one year and less than two years out of warranty.  No warranty coverage.  Garmin offered a replacement for a much reduced price.

I don't see a problem.

So you don't see a problem with a watch that is described as being water resistant to 100m failing after a short swim? 

I don't see a problem with a watch that is out of warranty not being repaired for free by the manufacturer.

But wouldn't garmin be interested in why a watch that they describe as ok to 100m failed in 1m? This isn't an issue about a warranty it's about quality control and providing an accurate description. If they said - don't take this in water I would understand. 

Jemesa1 said:

But wouldn't garmin be interested in why a watch that they describe as ok to 100m failed in 1m?

3 years is time long enough for the sealing getting damaged chemically or even mechanically. In the article Watch Wear and Care Tips | Garmin Garmin recommends avoiding exposure to the following chemicals:

• Hair dye
• Insect repellents
• Moisturizing creams and lotions
• Oils
• Perfumes
• Sanitizers
• Soaps
• Solvents, detergents or household cleaners
• Sunscreens

I guess after 3 years it is difficult to tell how often your watch was exposed to some of it. 

1. My Fenix 6 pro solar completely died a couple of years ago after a 30 minute splash in the sea jumping waves, Garmin replaced it as it was still within warranty, but I had to wait until I got back from holiday to get it. I’m currently away on an active (run/ bike/ workout mainly) holiday with my now out of warranty Fenix 6, debating if I am brave enough to wear it in the water and risk the same happening again (short term pain of active holiday without it and then larger one of paying for a replacement). I have noticed a little grease like substance leaking out from between the back of the watch and the heart rate sensor, this is what my previous watch was doing, should I consider the waterproofness compromised and err on the side of caution? We are looking at SUP and kayak type activities rather than open water swimming, but it is still likely to get very wet.

4488092 said:

should I consider the waterproofness compromised and err on the side of caution?

Visit a local watch repair shop, and ask them to make a water resistance test. That's the only way to see whether the sealing is OK or not.