Prior to this yellowing period, affected plants will have leaves that do not unfurl. After about one week most leaves will unfurl making these trapped leaves visible to sunlight and what we are seeing are sun-starved leaves.
There will be minimal, if any, effect on the yield of these plants. Twisted whorls typically occur as plants transition from young pre-V5 seedlings to the rapid growth phase we are entering.
The picture is a corn leaf that experienced onion leafing and the leaf area that was twisted and bent is now exposed to sunlight, displaying the yellowing.