The basis for this rumor is a discovery published by XDA Developers, concerning a recently released update for the OnePlus Camera app.
XDA senior member Some_Random_Username found code strings in the update that reference a 64MP sensor. It also mentions that the camera will also work at a lower 16MP resolution, which will make for smaller photos but more effective performance in low-light conditions. For comparison, the OnePlus 8 and OnePlus 8 Pro both use 48MP sensors in their main rear cameras, which can also take pictures at 12MP too.
While we really like the OnePlus 8 Pro and the photos it produced, its cameras were not class leading. That's why the potential introduction of a larger sensor has us interested, particularly because we're about to see the launch of the Galaxy Note 20, the biggest Android release of the year.
From what we've heard rumored, the standard Note 20 will have a 64MP camera installed. However, this isn't the main sensor, but rather its 3x hybrid zoom telephoto sensor, the same one we saw on the Galaxy S20 and Galaxy S20 Plus. Its main camera uses a smaller 12MP sensor.
The Galaxy Note 20 Ultra is thought to be using an even larger 108MP main camera, the same one that the Galaxy S20 Ultra uses. However, testing the S20 Ultra's photography skills revealed that getting this enormous sensor to behave was a tricky task, particularly when it came to getting it to focus properly.
Samsung looks to be responding to this with the addition of a new laser autofocus sensor on the Note 20 Ultra. However while this new laser sensor may be an improvement, it's not certain at this point whether it'll be as good as a normal camera sensor like this rumored 64MP OnePlus camera.
Hardware isn't the only factor to consider when it comes to evaluating a phone's photography though. Software processing can be a huge benefit if done properly, as Samsung, Apple and Google have proven by sticking with smaller sensors but still leading the pack thanks to excellent computational photography.
There aren't many OnePlus 8T leaks to go on yet, but we'd expect the rumor mill to gear up as we head towards October, the month OnePlus usually unveils its T models. We're expecting the 8T and 8T Pro to use a Snapdragon 865 Plus chipset, which should make for a performance boost over the standard 8 Series, and for the potential introduction of 65W fast charging for even quicker battery fill-ups.