Ugh, that's really unfortunate. I put in Trex many years ago when it was the go-to and it immediately grew black mold inside the boards. Nothing takes it out. Trex was sued for it but there was no remedy for new customer. They would do nothing. I hate them and tell everyone to not buy Trex. I hope you get your project done and it turns out great. Just keep spreading the word to never buy Trex. If they have social media, post there, too.

Where did you order your material from? Trex boards have a product identification lot code check the code to make sure they came from the same lot. I have been installing Trex since it came out and never had that issue, except one time, the customer purchased materials from some lumber yard, and out of 40 decking boards, 8 of them had different lot codes and the color was a bit off.

If that's the case go back to where you got them and they should handle that issue.

As the trim boards go, if you using clips, the decking board is grooved, trim boards are solid, and they are always a shade off.

Good luck.