Pretty much no issues since I started cleaning regularly. I also didn’t have chickens for about a year, but that choice was made later, and I’ve found a different feeder that keeps out the wild birds but it doesn’t seem you have that problem. You don’t have to clean really often, once or twice a year depending on your preference and how often you add chicks. I do it yearly before I apply new whitewash to the interior.I have only cleaned with vinegar and water in the coops. My kids are so sensitive to harmful chemicals I hadn’t considered that also wondered how much that could/might hurt birds? Did you have a lot of sickness that went away after cleaning??
Activated oxine and Virkon S are both approved for use around your animals. I have a lot of allergies and chemical sensitivities, both skin and breathing issues, but I can use them both with no issues. I tend to rotate between the two.