WA PEBB Plan Premium at UHC up 56.3%

Just got my statement with the news about our WA state Public Employees Benefit Board UHC Complete Medicare Supplement Insurance premium increase for 2027 - for coverage of my spouse and myself monthly premium is going from $434.81 to $679.30.  I saw AZ was going up 30% what is the situation in other states and why is it so different from one to another?