I found this pretty interesting https://www.hackster.io/news/researchers-spot-silicon-level-hardware-trojans-in-chips-release-their-algorithm-for-all-to-try-ba00bbd56248

If I'm reading the article right, the title is somewhat misleading. The researchers did not actually spot Trojans at all. They spotted their own design changes, which I suppose were not related to Trojans. Trojans only come in to things in that the same method could be used to spot Trojans in principle.

I read it that they simulated trojans and were able to detect the gds vs Si mismatch. Real trojans would require an actual adversary.