As suggested before, the clean way of deep copying objects having nested objects inside is by using lodash's cloneDeep method.
For Angular, you can do it like this:
Install lodash with yarn add lodash
or npm install lodash
.
In your component, import cloneDeep
and use it:
import * as cloneDeep from 'lodash/cloneDeep';
...
clonedObject = cloneDeep(originalObject);
It's only 18kb added to your build, well worth for the benefits.
I've also written an article here, if you need more insight on why using lodash's cloneDeep.