@ptrblck
Thank you so much for your help.
Eventually I “work around” the problem by doing the following:
avoid “self.config=config” referencing, but directly instantiate it’s content:
Was:

in init
self.config = config
…<later in the body, self.config were referenced as>
self.config.center_variance
self.config.size_variance

Change to:

in init
#self.config = config #comment out
self.config_center_variance = config.center_variance
self.config_size_variance = config.size_variance
…<later in the code, no more reference to self.config >
self.config_center_variance
self.config_size_variance

Then the SSD() is deepcopyable, but QAT still having problems…