You might have a tag on the hinge side of the door. Ours appears to be made by Lippert.
Trekwood might be a source if you need to get a whole door. I’ve found that you need to call or email them - sometimes they are out of stock or clarity needed on the website description.
If you strike out on just the frame, here’s a link to an eBay seller, selling used RV doors - tag looks the same. Beware that some are damaged (and whole door could be the wrong color. Might be worth an email to them.
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