My guess why higher your reputation is the fragile it becomes is because the more reputation does not necessarily make the effects of negative thoughts against the company weaker but rather makes people trust you more and willing to stick around for longer. If a well reputed company or a person does a major mishap, people are more willing to give them the benefit of the doubt and have a higher chance of going back despite the mishaps as long as they are not very big or in a way that sends red flags because they trust the person or company due to having a good reputation

Then why is it so brittle in big companies? Because the mishap mentioned here of Stripe rescinding the candidate and others we tend to hear about are pretty major and enough to erode trust significantly and in turn reputation.

When smaller negative things like Amazon not donating a large amount of money to curl but it was short lived and faded easily and probably nobody remembers it but bigger bad things we frequently hear about big companies such as poor work environment in Amazon is pretty hard to forget and no amount of good reputation unless something big enough shows that it is not true it will be on the back of mind for a long time.

In smaller businesses people expect negative things to happen more frequently and nobody remembers since it is normal for people and reputation is unaffected unless something extremely bad happens.

Hence even if you have a good reputation negative things will break it more often than in smaller companies because you have far higher standards to hold to maintain while small companies dont't and their reputation does not go down as much as bigger companies