word choice - Photo creds or photo cred?

A lot of people nowadays use the phrase "photo creds" eg:

Here's an awesome photo of me! Photo creds to John!

Creds usually means credit or credits. But then you get the sentences:

Photo credits to John

Photo credit to John

Which of these is correct? If it's the latter, then it should be "photo cred to John" abbreiviated, right?

Answer

Cred is recognized as an informal slang abbreviation of credibility, not credit:

noun,

Slang.

1. the quality of being believable or worthy of respect, especially within a particular social, professional, or other group:

If you wear this t-shirt, you’ll be earning geek cred.

Both chefs have plenty of Southern cred.

According to the Urban Dictionary, creds is the informal slang for credentials or credit:

Credentials earned in life by experience.

Credit given.

He talked about being in prison like it gave him creds.

Photo credit to John, is the idiomatic expression to give John credit for his creative initiative. The expression credits to is 7 times less common than credit to in searchable written media, and is predominantly used for financial credit transactions. All these expressions are linguistically related in their etymological root: credo:

late 12c., from Latin, literally "I believe," first word of the
Apostles' and Nicene Creeds, first person singular present indicative
of credere "to believe,"

perhaps from PIE compound **kerd-dhe*- "to believe," literally "to put
one's heart"

(cognates: Old Irish cretim, Irish creidim, Welsh credu "I believe,"
Sanskrit śrad-dhā- "faith"). The nativized form is creed.

General sense of "formula or statement of belief" is from 1580s.

The cutting edge of word evolution is a double-edged sword: you can make words mean anything you want, but then you never can be sure exactly what they mean.