The Lex in season 11 is the returned Clone introduced in the series finale...he lost his memories when Tess injected him with the memory serum. He had all the same memories as the original Lex did, who I believe died when he was blown up in the truck by Ollie.
OK, that much I remember, but this is my point: I could understand that if they hadn't been able to get Rosey to come back for the finale, that the story would've required using a clone who most likely looked like Observer Lex from the S10 premier, in order to explain why he was physically older than Lex Prime.
But since they DID talk MR into coming back... Then why not have him be the real thing? And say that it was a clone that got blown up in that truck while the real Lex laid low until he felt the time was right to return. This is the part I don't get, because there was no real reason to go with a clone-Lex at that point in time, as Rosey's appearance was a one-shot deal at that point.
I'll get off my soapbox now and go back to reading the comic.