Light Xithricite Mining Beam's extended description claims Xithricite: 200%, but the actual rate is only 150%. I don't know which of the two is the bug.

Thanks for the report. It is supposed to be 150%. It should be fixed now.

Seems the fix didn't make it into the latest release? It's still a mismatch in Vendetta 1.8.608. Just to be sure we are looking at the same thing:

/lua print(InvManager.GetInventoryItemPrototype(1244253786):GetParameter("OreXithricite"))
1.5
/lua print(InvManager.GetInventoryItemPrototype(1244253786):GetExtendedDesc())
Range: 100m|Rate: 1.5|Heat: 1|Xithricite: 200%|Grid Usage: 4|Mass: 500 kg|Volume (as cargo): 1 cu