Battery back
Why is the iPhone battery pack flashing red?
You're right about no mention of red. You can call Apple and ask what it means. Refer to this document for ways to contact Apple --> Choose your country or region - Official Apple Support
Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support
Other possibilities:
Not all people see colors the same way. Apple's amber may be your red.
Going on the basis of general patterns with things, green usually means "go" or "good", amber means "slow" or "not good but not bad", and red mean "wait" or "stop". Maybe Apple just figures that anybody seeing a red color will know that it almost has no charge. I don't own that battery pack but in the 5 others I do own it is that way. Plus at traffic lights.
