[mokus]

That article only says it’s the first this century.

[plantain]

As long as you define century as 2000-2100, and not 1922-2022...

[avgcorrection]

“This century” is fixed to start at 2000 until 2100, same as this decade is 2020–2029.

“Last hundred years” for the former interpretation.

[quietbritishjim]

That is how "this century" would typically be understood