I don't know what the process is for finding a reviewer :), but this is an important correctness change in upstream Wine to preserve the intent of a GetAsyncKeyState fix originally authored for Photoshop CS5. The keydown cache is important for performance in mainstream Wine (it was deleted in Proton due to faster server IPC access), but the cache needs to be invalidated on edge detection whenever keydown status changes. The original fix from 10 years ago was to add an edge trigger that forces keydown status to be refreshed across all threads whenever one thread detects a key change.
This change covers an additional edge which was missed at the time - input message handling can update a single thread's key status without running edge detection logic. It manifests in some open-source game clients, such as Second Life, as an occasional inability to turn properly while running forward (due to inconsistent keydown state across threads).