Mine tax code was changed after I start receving my pension

My tax code before receving pension was 1257L to 493LX whats the reason of that change ? From 6 April 2023 to 30 July 2023 I earned £8580. From October 2023 I started to receving pension. Does amount I earn plus my pensions till March 2024 with tax code 493LX will make any changes to my tax paid on the end of the tax year 2023/2024? How to calculate my tax paid with that tax code and does amount before tax code change is included? Thank you for your help. Have nice day.

Hi franeknowak,
We would need to access your record to review your  tax code.
Details of how to contact HMRC here:
Income Tax: general enquiries
Thank you.