These are just my wild guesses but, for Switzerland, I’d say:
Low interest rates are mainly a function of the strong frank (and, reversely, the weak euro and the european economic/financial problems). Inflation went mainly into higher imported prices, which were already high. For us, with big export and import balances, inflation is a processus that is relative to the inflation faced by other countries. Our interest rates were/are low but the ECB and FED had it set low too, so we mainly went business as usual with a policy that favoured exporting companies.
For the US:
Low interest rates benefited businesses and those who borrowed to buy assets. The compensation gap has increased, so additional company profits went preferentially into the hands of executives, some well paid technical jobs and shareholders. That money went mainly into inflating investment assets prices, like stocks and real estate. Few of the newly created/available money went into general consumption or, at least, not enough to create an inflationary shock.
In 2020, the money went into tax credits, unemployment benefits, stimulus checks and PPP loans to businesses. At the same time, foreclosures were blocked and real estate asset prices went through the roof, so people could feel safer and had more money both available, and that they could get on credit, to spend, as well as more willingness to spend it from 2021 onward since they had been restrained in their opportunities to do so the year prior.
Demand for ordinary consumption goods went through the roof, which is one part of why we had inflation this time. The other part are supply chain constraints, that made things baloon from the suply side of things.
My take is that, in order to maximize its total wealth, a capitalistic society has to concentrate most of its riches in the hands of few, so as not to funnel inflation too widly. Those people can then use their wealth as leverage to keep things working that way, which prevents the collapse of their riches, as well as the whole capitalistic model they’re built on. A more redistributing society would hit an inflationary threshold earlier, since more of the available wealth would be spent regularly. The median member of the society would be richer, but the total wealth available in the society would be lower. The limit on that system is reached when inequalities are great enough to funnel social disorder, the fear of which is what should keep the more wealthy people (speaking of the top 0.1%, not just average higher end middle class) in check.