The London mayor is only responsible for TFL red routes so you'd expect the highest penalties on these.
Last year, London Councils raised penalties from those set in 2011 for the London boroughs but they are a bit lower than TFL's and still have two bands for inner and parts of outer London.
Scotland raised penalties recently.
We've seen at least one experimental higher rate elsewhere (Bournemouth).
Clean air zones have higher penalties than parking.
This report recommended increasing civil penalty charges under Traffic Management Act 2004 to £130 (where higher rate applies) / £100 (where lower rate applies) owing to inflation at least as the £70/£50 regime dates back to 2008.
https://data.parliament.uk/DepositedPapers/Files/DEP2025-0736/PATROL_BPA_Research_On_PCN_Levels.pdf