As per this article Gchen (Dup dev) wrote 3 years ago:
It has not been optimized for cold storages as of now, but in the future it will.
[Duplicacy caused me $122 USD of cloud storage cost (file operations) in just 1 month. Arq 6 cost $22 USD for 6 months. How to fix that?]
Has this been done?
I would be a happy Duplicacy-User, if it supports Glacier or GCS-Archive.
best regards
Andreas