NCSoft has confirmed the only Experience Crystals that will be removed are the ones obtained from Garden.
This is NCOSFT Inquiry Response Notice.
Hello. This is NCSOFT.
This is a response to your inquiry.
Date of Response : 10/09/2023
Hello,
Thanks for contacting Aion Support.
Only [Event] Experience Crystals that were obtained from Garden Of Growth event will be removed with the end of the event.
I hope this information clarifies your issue. If you have any other questions, please feel free to let us know.
Regards,
NCSOFT Support Team