That one’s not really a red flag. If they keep all of the same assets and lighting settings, UE5 will look damn close if not identical. Updated code doesn’t mean it magically updates the graphics, though I bet plenty of UE-sourced assets have easy upgrade paths.
For an example of a game that doesn’t suck that did this, see Satisfactory. It looks nearly the same. Though I think some things have improved slightly, since they at least enabled a few things.
Then why upgrade to UE5 6 or so months before launch for minimal improvements?
Same as any library/framework upgrade in code: if you don’t upgrade, you will not eventually get any new features/security updates/asset etc. If you have stopped development, then no point, but if you plan for support game for longer period, it makes sense. Also in the future if UE 7 brings something awesome, upgrade from UE5->UE7 is much harder than two simpler version upgrades.
And ofc this thing is clear scam, so this was just in general