UPDATE 2020-10-26 23:08 IST
The chosen reviewers have published their reviews for the OnePlus 8T. Leo X made a convenient forum post about the same.
"The Lab" is a unique concept OnePlus first introduced in May 2016 with the OnePlus 3. The OnePlus 6, 6T, 7-series, and 8-series were part of the program.
The 7T-series' had it slightly different - participants had to buy the device first, and winners could choose between a full reimbursement of their purchase, or a custom device with their name engraved. This year's iteration (for the 8T) is similar to previous ones - if you're selected, OnePlus will ship the device to you, free-of-charge, before the launch event. If you win the review competition, you get to keep the phone. Otherwise you'll have 1 month to ship the device back to OnePlus.
What's more, if you're one of the top 3 reviewers, OnePlus will repost your review across all their social media channels - giving you even more exposure. Every reviewer is expected to adhere to the following timeline, and be active in the forum + participate in AMAs (ask me anything) once the review period ends:
In total, only 10 reviewers will be selected, so make sure you make your application stand out. Try adding links to your existing work, if you have any - photography, news articles, blog posts, YouTube videos, etc). You can also check out this thread, where OnePlus explains the story behind The Lab.
If you're looking for some inspiration, check out previous reviews by The Lab reviewers:
Fun fact: AnonymousWP, an Oxygen Updater team member (and a mod of the r/OnePlus Discord server), is a OnePlus 7 Pro Lab winner. Check out his review as well.
Keep in mind, however, reviewers will have to sign an NDA before they receive the phones. Check out the official post on OnePlus forums, which contains more information, and a sign-up link as well.
If you're rather proceed to the sign-up form directly, click here. You'll have to answer a few questions, including a short write-up (about 250 words).
Applications opened today, and will remain open until 11:59PM EST, September 27th 2020. Selected reviewers will be announced on September 28th 9PM HKT.
Best of luck! If you'd like to know more about the upcoming phone, you can do a quick Google search for "OnePlus 8T leaks & rumours", otherwise we may write a round-up article soon.
Source: OnePlus Forums