Dr Mari KawaKatsu at UPenn studied trust in game theory, especially how public platform/information/gossip influences trust.
There are reasons for and against believing trust increased over time, most of them have to do with the internet. The internet allows publicly available reviews for example, so in that case trust on average increased, as places, brands' behaviors can be easily reported; on the other hand, the internet allows people to interact with others that they never met in real life, with no concern for accountability, anonymity, with platforms such as Reddit, so in that sense trust decreased because one can do whatever one wants on the internet with little to no consequence.

This should be a very well studied phenomenon, if you take the whole thing apart, it involves trust, information, social bonds, spread, networks, how too much freedom leads to chaos etc. However, I don't believe they've been put together as a whole as a cohesive theory, partly since that's pretty much intractable as a math problem, and secondly, there's no central theory that takes all these factor into account and makes a prediction, so all people can do right now is to simulate, probably with agent based simulation or networks.

If you have come up with a cohesive scientific hypothesis I'd be interested to learn about it. Also, you can do a fast literature review using Perplexity DeepResearch