Vector feature styling with colorMode=Random should let the user select an "ID" property.

[kring]

Feature IDs are not consistent across tiles, so we get problems like this (reported here):

We can solve this by letting this user select an ID property and generating the color as a hash of the ID. This way, the "same" feature (as defined by the selected ID property) will be the same color no matter which tile they're in.

It would be reasonable to default to the property with the ID semantic, if there is one.