Weird artifact when using anti aliasing

[OscarCapac]

There is a weird artifact that can randomly occur while anti aliasing is enabled.
It is relativily hard to notice when playing normally even it seems to occurs at a fixed spot on the screen. It seems to appear more frequently if there is smoke from Mario punching that intersect with a wall or someting,
However pausing will show the artifact 100 % of the time and was the only way I could take a screenshot of it happening.

It looks like a small group of 4 pixels that is mostly grey but can change color. I think the color is related to what is on screen.
You can see the artifact on the bottom right of the pause grey area on the screenshots.

Screenshots taken with Luma3ds. I then corrected the aspect-ratio because I was playing in 800px mode.

Top row : AA disabled
Bottom row : AA enabled

I was also playing with the 60 fps patch.

[mkst]

I've seen it too; currently got no idea what causes it, and why only with AA, very weird.

I plan to spend some time going through previous commits to see whether any functionality has regressed (along with any performance issues) to see if I need to undo any of my 'improvements'...

[ryotoko]

Is it always occurring in this same spot? This is the same location in both examples

Also, how is 800px related? Does it occur in 400px AA mode?

[OscarCapac]

It happens regardless of the 800/400px mode.

While it happens on the same spot while pausing 100% of the time, I can't confirm that it occurs on the same spot while playing normally because it appears so briefly and I haven't be able to take a screenshot in this configuration.
However there is a good chance it's the same spot because it always seems to happen on the bottom side of the screen.

[mkst]

It doesn't happen in the original Gericom build. It is bizarre that its the same spot and only when AA is enabled.