You are referring to the eBay feature called “Offers to Buyers”. From the eBay website:
“Send offers directly to interested buyers, negotiate offers, and make counter offers to help increase your conversion, or automatically provide the best offer to buyer when creating your listings.”
Do not mix this feature up with the “Best Offer” listing option.
While GarageSale supports the “Offers to Buyers” feature, you can’t enable “send offer automatically” option here. You somehow must have enabled that option on the eBay website directly, that’s my guess.
Please scroll down to “Automatically send offers to your interested buyers” on the eBay help page here to learn more:
You might want to disable the “send offer automatically” option in your eBay settings on the eBay website.