Hi @Naturenex - hope you're keeping well!
I think we should take a quick step back, because there's quite a bit to unpack with your statement and question. Let's try to organize our thoughts a bit and make sure we understand how the systems work.
In general, I think a quick search at Support.ezoic.com would really help you to understand what's going on, you'll see quite a few guides from there used in my response below 🙂.
"After adding Ezoic to my site, it automatically reduced my AdSense daily earnings"
This is entirely expected, since your traffic isn't going to AdSense versions of the site any longer. You're traffic is going to Ezoic versions, that shouldn't be showing any AdSense ads directly. This is entirely expected.
https://support.ezoic.com/kb/article/how-do-i-turn-ezoic-on-and-off
You have 10% of all visitors seeing AdSense versions, if you were earning between $2 to $3 a day, 10% of that revenue is $0.20 to $0.30 you're seeing.
Taking a further step back, you have AdSense mediation running on the site, which means AdSense is competing with the Ezoic ad partners on the Ezoic versions of the site. There's no need then to send 10% of your traffic to an original setup, since that ad partner is already a part of the Ezoic bidding process.
(see bottom of this article: https://support.ezoic.com/kb/article/google-adsense-and-the-mediation-app)
This guide helps explain further: https://support.ezoic.com/kb/article/who-are-ezoics-ad-partners-and-can-i-keep-my-own
"Should I remove chrome extension and place the ad using normal placeholder to set up."
I think there's some confusion here, because removing or adding the Chrome Ezoic extension won't actually affect the ad placeholder setup on the site. Once you've created a placeholder using the extension, you'd have to delete that placeholder manually, either through the extension itself or via the Ezoic Dashboard > Monetization tab. Again, once a placeholder is created using the extension, it remains regardless of if your browser still has the extension installed.
Further, there's no difference in a 'hard coded' placeholder created through the Dashboard or a chrome extension created placeholder. Again, once they're on the page they're there until you delete them manually.
It's never a good idea to delete placeholders if they've been running for any period of time (unless they are causing layout/functionality issues, or there's compliance issues). It can really hamper the Ad Tester testing process - if you're looking to optimize, you can certainly can, but it would be by adding more placeholders to increase the potential revenue. One great way to do that is via the WP Plugins ad tester options:
https://support.ezoic.com/kb/article/setting-up-ad-tester-placeholders-with-the-ezoic-wordpress-plugin
I hope this helps to clarify a bit and should help to get you on your way to a more optimized setup - and if there's more questions feel free to ask! We're here to help!!