This has always been the case with Theia, even in 2.6.4, but no one else seems to have ever reported it.
Theia, at most setting parameters, produces grid patterns on motion. (At least at DVD resolutions. I have not tested higher. [Both Fidelity and Detail act the same. {Excluding 0 values.}])
Here’s some example images. These all have been ran through Theia at 100% scale, then passed through Proteus Manual with everything set to zero, (My test script was already set up that way. It would have been harder to remove it.) to show the grid patterns more clearly. (And also that’s how I want to use Theia anyway—as a denoiser before Proteus.)
Revert Compression: 0
Sharpen: 30
Reduce Noise: 60
Revert Compression: 50
Sharpen: 0
Reduce Noise: 20
Revert Compression: 20
Sharpen: 30
Reduce Noise: 92
And how about some totally unrealistic settings? This is just to exaggerate the artifacts that generally show up. In case you couldn’t identify them from the other examples.
Revert Compression: 20
Sharpen: -100
Reduce Noise: -100
And now, let us go crazy trying them on a black and white movie.
Revert Compression: -100
Sharpen: -100
Reduce Noise: -100