No one has mentioned that bugs / glitches / exploits have been part of Gran Turismo ever since it's been online(?):
GT5 Prologue: Subaru max / min toe glitch (never fixed by PD)
GT5/6: 'reverse ride height' bugs / glitches / exploits (never fixed by PD)
The people using these had the same reaction, some (after it being explained to them) would understand and stop using it, others would take offence as they didn't see it as cheating, only using what was there in the game, others just didn't care - it made them 'fast'.
So why should it be any different now - these previous 'bugs' also affected either the online races or the leaderboards?
Whether something is fair or right in a game like GT is highly subjective and a never ending arguement, it's a huge can of worms.
Look at PD's love of 'cheat cars' within PP / BOP regulations, again, ever since GT has been online there have been obvious cheat cars in each 'class' - did this make it right or wrong to use them when other cars were available? What about driving aids, differences in view (cockpit Vs chasecam), corner cutting Vs '2 wheels on track, driving standards (what is/isn't acceptable contact) etc etc etc...
It doesn't make a difference whether this 'grip bug' is random or deliberate, simply because even if an 'advantage' is available to everyone, not everyone will use it. Does everyone use the 'cheatcars' in each class, nope, there were always some who choose something different.
Even if this 'bug' gets fixed you can still argue 'til the cows come home about what is an unfair advantage or what should or shouldn't happen, or what is right or wrong - that's just the way GT is, and more importantly, always has been.
Until PD genuinely fix this we don't know exactly how, why or who / how many the current bug is affecting.
If you don't think the current public races are fair, there's always the option of creating a room or series for you and your friends (who you feel are not benefiting from this 'bug').