Thank you for the suggestions. The turning radius and gain both stay the same in-game. I just did some more testing and think I found the culprit.
The issue only occurs while Logitech G Hub is running, so I related it to that.
I also realized the wheel does not return smoothly while the car is stationary, though it does while driving. When the car is stationary, it'll return in steps. Also, when I turn the wheel while stationary, it doesn't feel smooth. It feels like there are steps along the way (tightens and loosens).
Once I tab out and back in, the wheel is harder to turn and returns to center more quickly/smoothly while stationary, which pointed me to the Centering Spring In Non Force Feedback Games setting in G Hub.
This has always been unchecked.
If I check it, with the default value of 20, the wheel goes back to feeling the way it did before I tabbed out. Loose, steppy/shaky while stationary. Tightens a bit while driving.
If I check it and increase the centering strength in G Hub to 100, it feels the way it would after tabbing out and back in while it was unchecked. Tight, harder to turn, wheel returns more quickly while stationary, smooth, quiet.
If I leave it unchecked, my FFB changes to the tighter mode after tabbing out (original issue).
I have a feeling this is caused by some kind of miscommunication between AC and G Hub at launch.
When I first launch the game, it feels like it does with the setting checked and on the default value of 20. Once I tab out, AC and G Hub probably realize that setting should be off and the game's centering activates. G Hub's centering enabled and on 100 feeling like AC's centering could be coincidence.
I'm still confused as to which of these settings is correct. The mode where it's tighter feels better, but I'm not sure if any FFB effects are lost since the wheel is always tight. Does one or the other sound correct to you?
Also, my car's horn has been hoking as I typed this entire message.