I wouldn't worry about the colour of their poop. the main concerns are how they look (small, strung together, or wet poop) and really not the color imho. their color poop has so many different factors, but it usually comes down to their diet. darker poop isn't a bad thing, it just means their diet is richer, which isn't necessarily a bad thing either...
for instance, outside rabbits are likely to have darker poop as they're often eating grass or forage. this is usually richer than hay. in the spring, grass is very very rich, so poops will often go darker then.
indoor rabbits are more likely to have golden poops due to not eating as much forage, mostly pellets, veggies and hay. they're usually on a more hay diet with little grass compared to the outside buns.
but even how "rich" their diet is can vary from the hay you buy, to the cut it is, to the veggies they had, to the forage (fresh or dried) they were given. theres so many different factors around it. one bag of hay might be richer than the other even if it was cut at the same time and dried the same. its too variable.
tbh with you - and I might get shot for this - I don't understand all the hype around golden poop :lol: one facebook group I am in is so obsessive about golden poop and celebrating how wonderful it is, as if darker poop is bad. darker poop isn't bad at all. if it was strung together, small, runny, or bloody inside, then you'd have an issue.
my buns (even though indoor) have mostly always sometimes I get golden poops but its usually on a week when they haven't had much fresh herbs, dried forage or grass (from outside or grown indoors). it can vary on the hay too, as I rotate between ings and timothy & rye. ings gives golden poops and the timothy hay not so much. but its not something I'm concerned about as they're eating well, and their poops are large and healthy