For me, as far as multiple data layers with (very) different validities are displayed on same map which only offers 1 single time reference (time bar), this is always an issue (and a big one: wrong/incomplete info). All data layers on a map should be synchronized with currently selected time on time bar; otherwise, UI should provide the time reference of each of them. Nothing on UI provides the validity of all those data layers which are not synchronized with time bar. Of course user can disable them all, but this is just a workaround, not a solution.
It is somehow like a map which would display "T°C" values for NOW, then some other "T°C" values for "once upon a time", while only NOW time reference is provided...
