I’m quite confident that my error was an insufficient amount of brown matter to balance things out.
My chicken run compost is mostly leaves and grass clippings, with whatever poo the chickens drop while running around. My chicken coop litter is a dry deep litter mostly of wood chips, so when I clean out the coop and dump the coop litter into the run, it's still mostly wood chips. I still let my chicken run compost age for at least 6 months before I use it in the garden. Mainly, I dump my compost in the garden in the fall and just let it winter over.
I mixed some chicken run compost with new soil (about 50/50) when I made my new hügelkultur raised beds this spring. My peppers in those raised beds exploded with both growth and peppers. I was harvesting peppers until about mid-October, which for me here in northern Minnesota is a record. The only thing I will do differently next year is that I will cage my peppers from the start. The peppers in that bed grew taller than I have ever seen in my gardens, and they got top heavy and started to fall over. So I had to stake them to keep them from falling down. But those are problems everyone could hope for in their garden.
I’m glad to know fall leaves are a good brown source though! I certainly have an abundance.
I read somewhere that, pound for pound, leaves provide more nutrients than cattle manure. The tree's roots go down deep into the ground and pull up all kinds of good nutrients which get transferred to their leaves. When the leaves fall off the trees, they replenish the top soil in a continuous, natural cycle, when the leaves break down. Those leaves you have in your yard are like money on the ground. Take the time and effort to compost them and reap the rewards.
If you want to sped up the leaf composting, you can chop them up into smaller bits by using a push mower with a bagger. The smaller the bits, the more surface area they have and the faster they will turn into compost. I just mow up my leaves with my riding mower and throw them into my chicken run, and let the chickens tear them apart. I have seen some people using an electric leaf shredder which greatly reduces the bulk of the leaves. Some get a 16:1 reduction ratio. If you want faster composting of your leaves, that would be a good option to consider. Once you know the value of those leaves, you won't want to throw any away to the landfill.