You reminded me of two CN isekai, one is where initially the MC isekaied to ancient China, but then turns out he didn't isekaied to ancient China as it is the future Earyh (Planet of the Apes/ a ton of JP games.)
Another one also starts with MC transmigrated to ancient China, but then turns out he wasn't normal salaryman as his past incarnate was the grandfather of his current body, who yeeted the soul to find the golden finger in our world and then rushed back to steal his own grandson's body to become god.