It's entirely possible the things are made of some kind of SS that is not appropriate for the end use.
Or that the end user is unknowingly abusing it in some way.
Soaking SS in a strong bleach water solution for any length of time is a bad idea. It should not hurt it to use bleach water to rinse it out as a means of disinfection, but leaving the bleach water in contact with the SS overnight on a regular basis is a bad idea for any grade of SS. In reality you don't need a very strong solution for disinfection,it does not need to contact the surfaces for all that long, and chloride cracking is not as big a deal at low temperatures. So use your head or a different means of disinfection.
No SS is really stainless and all off them can and do corrode. They are all more resistant to corrosion than steels, to one degree or another.
It's also possible that if you are using a fairly thin SS container for heating water the repeated heating cycles are causing a problem. It expands and contracts as it is heated and cooled and if the material has impurities in it, those areas may not expand and contract at the same rate as surrounding material, leading to pinholes.
It's not unusual to find Chinese made steel that has very hard spots in an otherwise fairly soft (at least for steel) plate. It's because they don't worry too much about the steel being perfect, and a lot of their steel is mixed with whatever scrap they can get in the rest of the world and ship there. In fact, China is a huge importer of scrap steel from the US. But when they make new steel plate out of scrap, its not unusual for some hard tool steel to get mixed in and not get mixed up very well so you end up with hard spots in the plate.
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Warning - I am not an expert on anything having to do with this forum, but that won't stop me from saying what I think.

Bob