Apparently there is already Acknowledged ticket (#29890) back on Alpha phase 4 and frontier wanted input on what paint jobs are affected. Pls go in and add your comments on the link below and vote on it so it gets prioritized.
The ticket details is as follows:
Metallic paint jobs are now matte
Greetings Cmdrs, We are aware of issues with certain paint jobs looking visually different in Odyssey when compared to Horizons. We are looking into this but to assist us with this I'd like to ask a small favour – If you notice this on a specific paint job, please add a comment stating the affected paint job. Many thanks in advance! QA-Jack o7