Mine was gasket from what i could tell.

 

For reference; My 2018 is fault free with 60k miles and use to run 89 until the gas cost rose then went to 87 octane gas with 10% ethanol.
The result is no ping, fuel milage seems better and power is the same, to my surprise.
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Look at reply #88 of this thread to see the update to repairs by the poster as proof 87 will run in a fault free 5L.
If there are no faults, the system should be able to adjust to 87 octane and run without an issue as it was designed to do.
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A motor with excessive or long term ping should be able to be diagnosed using a Scanner that can look at live and stored data if the user knows what to look for.
In searching the data, some part of that data will indicate or be suspect an issue is present but not tell the fix which must be looked for..
For example, the Long Term Fuel Tables can be shifted rich (+ side of zero) if there is too much intake air due to an intake leak. This shift is the system attempt to do fuel corrections to counter excess air up to a point it cannot correct it. Then you hear the result as Ping or Spark Knock a more severe form of Ping under throttle load applications.
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What is Ping? it is an Air to fuel ratio that is too Lean. This results in combustion flame travel 'to fast' after ignition, such that it results in cylinder pressures peaking to >>early<< before the piston to connecting rod alignment get far enough down the cylinder to push on the crank journals smoothly.
At these peak pressures, the pistons ring, cylinder walls ring, crank shaft rings and produced the sounds heard because the pressures cannot move the volume larger due to the piston-crank too much in >straight alignment.
Left to go on too long, can result is breakage, blown head gasket etc.
NOTE: As octane is increased, the flame travel slows. It's not that the fuel makes more power. Just that more/earlier ignition timing can be applied and cylinder pressures used over a longer period of time > correctly. This is added Torque production to the Crank..
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On a fault free motor that encounters some normal amount of low level ping, there is a Knock sensor that detects this condition. It's signal causes the computer to retard the ignition timing a number of crank degrees to stop the condition, hangs at that point awhile until Ping is no longer detected.
This could be seen on a Scanner watching Ignition timing action during Ping/throttle load conditions.