Yes. It seems like if anyone outside of yourself is involved in making an item listed as "handmade" they want you to list their info.
I don't use etsy, but after browsing their terms about this here's some useful info I found in the Handmade Policy:
Designers
A designer is a seller who has come up with an original design, pattern, sketch, template, prototype, or plan to be produced by in-house shop members or a production partner. Simple customization, such as selecting colors, shapes, or choosing from ready-made options is not considered design on Etsy.
If you are a designer and you are using a production partner to help make your items, you must also follow our Manufacturing Policy and disclose information about your production partner in your listings.
A production partner is anyone (who’s not a part of your Etsy shop) who helps you physically produce your items. We expect your production partner to produce items themselves, in their own facilities. A contractor or agent who outsources production is not considered a production partner. Examples of production services include, but are not limited to, printing, 3D-printing, casting, plating, engraving, cutting and sewing, and finishing.
And the Manufacturing Policy:
At Etsy, we value transparency. Transparency means that you honestly and accurately represent yourself, your items, and your business. For this reason, please share the following information in your listings (click here to learn how):
The name and/or descriptive title of your production partner(s);
The location of your production partner(s);
Details about the nature of your partnership and design process; and
A general description of the work your production partner does for you.
You may choose to keep the name of your production partner and details about your partnership and design process private (visible only to select Etsy admin), but the location and description of your production partner, as well as a general description of their work will appear on your About section and listings.
So yeah, it seems the issue is that if you're using a manufacturer they wanted to know that and also details about the manufacturer.