Maybe it's actually because OnePlus and Oppo are being banned in other markets like Germany and will likely be banned throughout the rest of the EU for patent infringement. Now they are stuck with a ton of handsets and not a large enough market to sell them in.
OnePlus has just launched the 10T as its mobile flagship refresh for 2022; therefore, you might assume that the last thing the brand would do is detract from this event with a potentially attractive haircut for the price of its other current top-end smartphone, the 10 Pro. However, this is just what has happened on the OEM's US and Canadian websites.