The twinkle effect is a typical artifact of noise reduction. Essentially, when performing noise reduction, you identify the frequencies of the noise and reduce the volume of these frequencies across the recording in order eliminate it. However, the frequency of the noise often overlaps with the frequencies of the actual audio signal, this is especially common with high frequency sounds such as cymbals, and the problem is even worse when the noise levels are high. The result is that twinkling sound.
When dealing with so much background noise it is impossible to eliminate it without introducing these other (worse) issues. Often a compromise is the best solution, instead of eliminating the noise, you simply reduce its volume. The remaining noise is sometimes enough to mask these artifacts, but make the recording easier to listen to.
That said, there is a good chance the recording did go through some sort of lossy compression. The twinkling artifact is not enough to indicate this though.
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