While the BBC are on the right lines when it comes to why sunset times happens earlier after the Solstice than before the Dec 21st event, the explanation is unsatisfactory-

https://www.bbc.com/news/magazine-30549149

On the December Solstice, the North pole is furthest from the light hemisphere of the Earth, thereby creating the largest circumference where the Sun remains out of sight. At lower latitudes in the Northern hemisphere, the time period between sunrise and natural noon is symmetrical with the period between natural noon and sunset and the shortest period within the annual cycle-

https://www.timeanddate.com/sun/uk/london

From that period onwards, the length of daylight increases as per the values of December 21st and December 22nd.

Three weeks the other side of the Solstice the values are different as registered by a clock although the symmetry between the sunrise/noon and noon/sunset in terms of a time period is maintained.

Much like DST where the foundations of the 24 hour clock are anchored to the sunrise/noon/sunset cycle, the discrepancies between sunrise and sunset times before and after the Solstice are functions of human timekeeping.

This would only interest those who use the central Sun and noon as an anchor for every rotation rather than those who appeal to the daily change in the position of the stars.