Seems Finder Extensions are no more on upcoming macOS 15 Sequoia, at least on the first beta.

Posted on https://forums.developer.apple.com/forums/thread/756683 to see if anyone else can confirm.

✅✅✅ Fixed in the upcoming macOS 15.2

https://developer.apple.com/forums/thread/756711?answerId=812625022#812625022

Workaround for macOS 15.0 - 15.1

There is a fix implemented in the Keka Helper v1.2.0 since Keka v1.4.4:

👉 https://www.keka.io/finderextensionsequoia