Finding that OnePlus was limiting the performance of its smartphones did not align well with the user community. This was a practice that was apparently followed and not reported.

Now the brand has gone public to acknowledge this practice and provide its reasons for the situation. OnePlus wants to make sure that their smartphones have an excellent battery which is why they have adopted this practice in their latest smartphones.

The case is recent and showed that OnePlus was limiting the performance of the 9 Plus model.  it's a Discovery It happened by chance, when a user posted a tweet where he compared the performance of Chrome on this smartphone with that of others.
A deeper analysis later showed that this was a much broader scenario and that many applications were targeted.  Interestingly, standard applications have been immune to this treatment, and pressured hard when it comes to performance evaluation.
The brand is now public to clarify this situation and reveal why this limitation applies to app performance.  He indicated that he wanted to make sure that he could save battery power and prevent smartphones from overheating.

Our top priority has always been to provide a great user experience with our products, based in part on acting quickly based on critical user feedback.  After the launch of the OnePlus 9 and 9 Pro in March, some users told us about some of the areas where we can improve the devices battery life and heat management.  As a result of these comments, Our R&D team has been working over the past few months to improve hardware performance when using 300 of the most popular applications, including Chrome, by matching the application processor requirements with the most appropriate power..  This helped provide a smooth experience while reducing power consumption.  While this may affect hardware performance in some benchmarking applications, our focus as always is to do what we can to improve device performance for our users.

It has been clarified that OnePlus applies this limitation to a set of well-defined applications.  These are more than 300, including Chrome and others, and they are filtered by the requirements they impose on the smartphone SoC.

We will also be testing other OnePlus devices in our performance lab to see if these phones also manipulate performance in the same way.  If they do, we will delete them from the Android Benchmark.
- Geekbench (@geekbench) 6 July 2021

OnePlus revealed that it has been working on this procedure for several months, possibly after the launch of the 9 and 9 Pro models.  The idea came after receiving feedback from users, who showed areas where battery consumption could be reduced.
This is a change that could have a significant impact on the experience of using this smartphone.  The brand prefers to ensure better overall performance than to lose in areas that are frequently evaluated, such as the battery.