Here is an FFT of a DAC running at 48 khz reproducing -4 db white noise. It was recorded at 192 khz so you can see what happens above nyquist or in this case 24 khz. This lets you see the shape of the imaging filter in the DAC. This one uses a half band filter. Meaning instead of being down 96 db at 24 khz it is only down about 48 db at 24 khz. It continues to drop off being down to the basic analog noise floor by a little over 26 khz.
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In your example of a DAC only down -10 db at 22 khz (presumably running at 44.1 khz) you ask what happens just after 22 khz. The answer is depends upon the filter. If it were a very slow roll off, not reducing levels to -96 db until 40 khz, then a white noise signal would bleed over into a sloped response only being filtered out around 40 khz. Meaning some decreasing amounts of noise up above 20 khz.
Here below is the same DAC fed a high level tone near 20 khz. You see the tone, you see a low level of 2nd and 3rd harmonic distortion. You see imaging artifacts at 28 and 52 khz. The others are from various other sources just ignore them. The 28 khz image is at -116 db because of the filter. And the 52 khz mirror image is -97 db.
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In your example such a DAC with a slow roll off filter the 28 khz tone might be only -12 db down in level and the 52 khz might be only slightly lower than that.
NOTE:my frequencies may appear a little off from the label, but that is because this was captured during a sweep. So the tone was really more like 19,500 hz instead of 20 khz. Close enough to illustrate the point I hope.