Is $4,000 to siding change order a fair price?

I have a GC completing work for my home renovation, including re-siding done by a subcontractor. The subcontractor initially used the wrong material on one side because he hadn't seen the plans. After this, he asked me questions daily to ensure things looked good. During these discussions, we made some minor tweaks. After the siding work was complete, the GC (who wasn't on-site during the siding) sent me a $4k change order for these minor tweaks, which is 1/4 the price of the entire siding quote. I'm okay with paying for changes but feel the price is excessive and want to ensure I'm not paying for the subcontractor's initial mistake. I've requested an itemized breakdown of the changes but haven't received it after a month. We just received the Certificate of Occupancy and the GC is requesting final payment. He said he will provide the breakdown this week. This isn't the first time they've done this. Earlier in the project, they wanted to cut a corner on the front porch bricking, which was against the architectural plans. After I pointed this out, a change order for rotten wood (which his wife had previously quoted at $1k) suddenly increased to $4k. They held onto that CO for 2 months before presenting it. Instances like this make it hard to trust them; it feels like they either underbid, didn't budget properly, or are trying to increase profit margins by covering their mistakes or overages with inflated change orders.