Because Calibri is an easier to read font on screens, which is where a lot more reading is being done.
Since it was done as an accessibility measure, it is seen as something for "inclusion" which is part of the scary "DEI" (Diversity, Equity, Inclusion). So it had to go, because forbid we do something that makes things slightly easier for people.
The change to Calibri was meaningful.
Because Calibri is an easier to read font on screens, which is where a lot more reading is being done.
Since it was done as an accessibility measure, it is seen as something for "inclusion" which is part of the scary "DEI" (Diversity, Equity, Inclusion). So it had to go, because forbid we do something that makes things slightly easier for people.