The apple store installed this battery in my phone and it now says unknown!

No, you are misunderstanding what you read. It is referring to UNAUTHORIZED replacement batteries, not batteries replaced by Apple in an Apple Store. That means batteries replaced by 3rd party repair services, who do not have access to authentic Apple parts.

You should not be seeing the message on your phone and it means they didn't complete the replacement correctly. Take the phone and your receipt back to the Apple Store and they will correct this mistake.

Lisiaw wrote:

No they aren’t contradictory at all…I went in Sunday and the battery was replaced…walked out then went directly back in to ask why this message was there. Manager then say’s it’ll disappear in a few days…it’s 5 days later now and the message is still there

In that case, perhaps go back and tell them that it didn't, and they need to go in and properly reset the system.

Lisiaw wrote:

I read this article that says it will happen even to with an authorized apple battery replacement. https://www.theverge.com/platform/amp/2019/8/14/20805744/apple-iphone-battery-replacements-ios-safety-statement-unauthorized

If the article is true, it means I’ll never see my battery info under settings after this replacement

Not exactly. The idea is that maybe something like a salvaged battery from another iPhone is installed. The message will be displayed in that case since whoever does that won't have access to Apple's proprietary equipment to reset the condition.

Apple has already announced a DIY and third party repair program. It's unclear how they're going to handle battery replacements. My guess would be someone purchasing a battery replacement from Apple will have to pay a deposit and get it back with exchange of the previous battery, and perhaps they'll need to bring it in to get the message reset, which is done with Apple's proprietary equipment.

Return to the Apple Store and seek assistance there.

A repair has a 90 day warranty.

These two statements from your post above contradict each other.

1. ”Now I’ll have to go back and get help with this.”
2. “He said it should disappear after a few days.”

It shouldn't if the system was properly "paired" with the new battery. This is a message that can happen if it's not an Apple OEM battery if someone didn't follow all the required service steps.