I noticed this before the last 1.31 update. Not noticed it so much now.
I spent about an hour on two tunes i had previously worked on for the BMW M2 Competition & Nissan Silvia S14. I had both setup pretty close to where i wanted them.
I decided to drive both round Tokyo Express in an online lobby. Both cars were fast & handled really well. I really enjoyed racing them around.
A couple of nights later i went back to both cars in the same online lobby & both seemed to understeer & oversteer more than before. Something just didn't feel right with both cars. I was definitely slower in faster corners. It was almost like the tunes had changed slightly, but the setup was exactly the same...
I just assumed it was me. I haven't touched either car since the 1.31 update