It’s probably only a display bug - what OS are you using? My Android shows all my higher star kingdom incomes too low, but on Steam they show correctly.
Just noticed a weird bug today regarding Kingdom income.
My Silver star Kingdoms show 95 gold per day (20 base, 25 quests, 50 for Silver star) - looks good
My 2 gold star Kingdom shows 145 gold per day (20 base, 25 quests, 50 for Silver and 50 for 2 gold star)
But my 1 gold star Kingdoms show only 45 gold per day, when they should be 95!
My total gold per day appears consistent with this error too - it’s dropped from around 2,400 per day to only 2,100 since I upgraded a few kingdoms to 1 gol…