Libary installation

Hi there,
I work on a usermod in the WLED project and need an external library (ezButton)
When I regularly install it via the library manager, I have the problem, that upon compiling, the new library is not recognized.
On discord, I was told to add it into a “platformio_override.ini” file, but when I checked an old backup version of my project folder, I found that each environment had this library added:
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Why didn’t platformIO do it in my current setup?
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Furthermore, in the PIO library manager, all available environments and installed libraries are listed:
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How can I remove this bloat of unncessary environments?

Thanks for reading through all this :face_with_peeking_eye:
Cheers, Hannes