Steven Moffat has explained his choice behind Joy's plot in the Christmas special

https://metro.co.uk/2024/12/25/steven-moffat-i-wanted-give-tory-rule-breakers-a-kicking-doctor-special-22217788/

Steven Moffat explained why he targeted the government Covid rulebreakers with Joy's character in the new Christmas special (and also ruled out becoming showrunner)