yes, correct. it was not technically hidden in the liquid case.
I assume they could've done it hidden, if they didn't peg out aggressively, or not at all. But there might be technical nuance that makes that impossible.
I also think the transaction on liquid didnt reveal it was fraudulent itself. it was only caught on liquid because there were unpatched nodes that saw the tx as invalid, so the network split.
Of course everything was very visible on the main chain
