The situation is not 100% clear.
From the looks of it, Oppo and OnePlus will remain in existing European markets until at least the end of 2023. But the companies are not saying anything about their plans beyond 2023.
The companies also talked about the ban on the use of their phones in Germany due to a patent trial that ended in favor of Nokia. They released the following joint statement:
The injunction is currently limited to the German market. Oppo is operating as normal in other European countries. We are committed to our existing markets and are still actively working to resolve the issue with Nokia. Meanwhile, all users, including users from Germany, can continue to use their products, receive after-sales service and future updates.
According to popular insider Roland Quandt, Oppo will shut down its German team by the end of June. However, he added that this does not necessarily mean that she will stop working in the EU.