I wonder what the driving force behind that is?
I suspect it has to do with double taxation on income.
When I was working in Switzerland in the 80’s I had to still file with the IRS every year and report foreign earned income. At that time I believe anything over $75,000 per year was taxed again by the US federal government.
I am willing to bet that ALL of these Citizen renuoncers are WEALTHY folks (AKA the 1% ).
The USA is one of only 2 countries I know ( the other one being a small African country I can’t remember ) that taxes you based on your citizenship REGARDLESS of where you earned your income.
Germans who work in America and make money here are NOT taxed in Germany for the money made here. But Americans who make money in Germany are taxed IN GERMANY *AND* America.
There was a time when an ex-pat could open a Swiss account and deposit their money there without having to inform the IRS. Not anymore. America bullied Switzerland to inform the IRS of ALL American bank accounts and the Swiss CAVED.