iTunes Connect rejection, Deprecated UIWebView usage

Hello, I have a critical bug to submit.
I’m using Unity 2019.2.01f, and PlaceNote SDK v1.8.
I’m working on an app that I’m aiming to release on the App Store in the next few weeks.
On the last iTunes Connect upload process (May 15th 2020), the app has been automatically rejected during the processing stage .
Please note that the App has NOT being rejected on the App Store review, but automatically after the upload. It cannot be sent to review or tested on TestFlight.
The issue (reported on an automatic email) is ITMS-90809: Deprecated API Usage - New apps that use UIWebView are no longer accepted . Instead, use WKWebView for improved security and reliability. Learn more (https://developer.apple.com/documentation/uikit/uiwebview).
I tried to figure out the external plugin that caused the issue, by following this article: https://levelup.gitconnected.com/how-to-find-and-remove-uiwebview-uses-in-your-ios-app-d9395f7baacc .
In my case, on terminal, “cd” into the .app found on the faulted app archive (.xcarchive) and running

for framework in Frameworks/*.framework; do
fname=$(basename $framework .framework)
echo $fname
nm $framework/$fname | grep UIWebView
done

It returns “Placenote”. See attached image.
As far as I could find online there’s no new PlaceNote version available.
Could you please help fixing this issue? It’s crucial one for me, as I’m currently not even able to test the app properly. Plus it will be a constant rejection from Apple.
Thanks