A short time ago Google provided some clarification on some of the issues surrounding the Pixel 2 XL display. Most notably, confirming that there does not seem to be any evidence of any long-term issues with the display, and that the colors which some users are perceiving as muted are in fact the more natural tones that Google had always intended to offer. While the previous Google posting did look to answer two of the questions surrounding Pixel 2 XL issues, it did not answer all of the questions being asked of the Pixel 2 line in general. Like for example, the high-pitched and clicking noises that some Pixel 2 owners are reportedly encountering.
The reason the original posting did not answer those questions is because a Google Community Manager has since released a separate Pixel User Community post on that particular issue. One which firstly looks to confirm that any clicking noises users are encountering, are not something that actually affects the performance of the smartphone. While also noting that in spite of no adverse effects associated with the noises, Google does plan to roll out a software update "in the coming weeks" which will "address" the issue.
Unfortunately, the posting is quite short and does not actually detail what is causing the clicking sound to begin with. Or for that matter, provide any information on how the update will remedy the situation once it does start to roll out. So at present the only meaningful details on this, is that an update is in the works, is in the process of being readied for deployment, and will be sent out sometime in the near future. Which is similar to one of the answers provided for the sibling Pixel 2 XL display issues, as Google also plans to roll out updates to further help preserve the display and improve color vibrancy. While it seems likely the updates mentioned in both comments will roll out to both Pixel 2 devices, there is no suggestion that they will roll out together, or as part of the same update. In the meantime however, the posting does note that any Pixel 2 device owners who are experiencing the clicking noises can temporarily fix the issue by disabling NFC in the phone's settings.