You've got to get down below 30psi before it gets sketchy. At 40psi it can be bouncy - like when you take your MTB/CX/Gravel bike out for the first time after being on the trainer. It's really no big deal on a road bike at 60psi.
At lower PSI, you do have more sidewall travel though. This is good and bad. When you lose traction on 23c/100psi because you're over the bar giving it the business, the rear will hop as it unloads, skip,
instead of spin ( think we've all done this pulling away from a stoplight). Yes, this is traction loss, not something you did pedaling to lift the back end or that you tipped your weight over the front end (though these are factors) - high power cars with independent rear suspensions do this and performance cars with live axles do this under braking. With the lower tire pressure, the rear tire has got more choices other than grip or skip as it can deflect more, so it's less sketchy as long as the front isn't bouncing around.