I is

From the new Kesha's song

''I don't care who you are
In this bar it only matters who I is''

Is this verb usage considered way radical in the US?

I don't know. She is so strange, and her accent is weird, she pronounces

1. BACK as [bek] (so Chicagoan ''I ain't comin' BACK'')
2. GOT as [gɒt] (rounded vowel, in ''you GOT me'')
very Valley Girl-ish

Where is she from?

she's from los angeles, but also grew up in nashville, Tennessee

yeah, she's got a weird accent. her STOP and CLOCK are also a more central [a]

as for the "I is", that sounds like AAVE/Southern dialect to me.

I don't see anything odd about her pronunciations of "back" or "got", nor do I think that your transcriptions are accurate. Can you provide a link to what you consider the "normal" pronunciations?

Of course, it's rather complicated by the fact that there is clearly some electronic manipulation of her voice.

I think it's mostly the electronic distortion in that particular song ("Tik Tok") that gives her a "weird" accent. I listened to samples of her other songs, and in those she sounds like a normal American. When she sings "Backstabber," for instance, she doesn't say "bekstebber."

Read it as:

<It only matters who "I" is.>

Then it's grammatical.

I don't like this auto-tune effect (popularized by Cher in Believe).
What does that mean anyway
auto tune?

It's a digital process. If a singer sings a note out of tune, you can lift or drop it to the correct pitch.

You can also use it in an exaggerated form for distortive purposes (as in your Cher example).

That strange 'auto-tune effect' makes me hear something close to /a/ instead of /ɑ / in words like: got, not...etc..

also, her ''down'' is something like ''dehwn'' lol
it must be her southern Twang

I've also heard "I are".

In the song "Green Light". The lyrics are:

<<She said, What type of girl do you think I are. The kind that you meet in a bar. You think you can get whatever you want cause you some kinda star>>