You can't put all sentences into the passive naturally. when talking about yourself, the focus is generally on yourself, so which sounds better?:
I did it.
It was done by me.
IMO, the passive has to be used for a reason, and that sentence doesn't work. A form may exist, but that doesn't mean it can be used. The problem here is the 'by me', not the concept of 'having been understood'.
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