On a cold start, the tach redline reduces much like during break in and slowly increases to the 6500 rpm limit as the engine warms up. Reaches 6500 when engine temp is about 72C.
Yes, the Corvette has done this since the C7 in 2013. When the engine is cold the redline is artificially lowered, you can go past it but its indicating to you not to exceed the lowered redline until it warms up. Basically an indicator to not abuse the engine when cold.
Funny thing I was in manual mode the other day leaving my house and it "rev limited" before the red line. Unless I was totally mistaken, but I'd swear I was only at about 5k. Yes, the engine was cold.
What a coincidence! Just noticed that this morning on start up as I had to sit waiting. At first I thought to myself "cmon...why is it showing pre-break-in rpms?!?!"...then it started to adjust higher.