Found a setting for handling this under the filament cooling.
It’s called Layer Time
https://wiki.bambulab.com/en/software/bambu-studio/auto-cooling
In other words, this feature (or at least a way to auto slow down just for the layers where it is needed) exists.
Sadly it uses the minimum speed setting as a limit for max time per layer. Ideally it would:
If layer takes long enough, settings have no effect.
Otherwise slow down printing of the layer.
If minimum speed not met by slowdown needed, print at minimum speed and add pause (at purge tower?) after layer.