Well you will go over the tax free limit in 25/26 and since State Pension doesnt carry tax deductions the amount you now owe must be deducted from your private pension because I assume you are a PAYE victim!
Thats the legal reason but....

It is a disgrace that despite warnings "her from accounts" knowlingly failed to change in her budget a situation where the increase in the Triple Lock would push pensioners into tax or in some cases, even more tax.
The same pensioners who have lost their winter payments.

Meanwhile they Cabinet seem to swan around the world without regard for cost.