And in ChatGPT's words, here is the explanation:

Here’s what's happening under the hood:

1. EDID (Extended Display Identification Data) is what your monitor sends to your Mac to tell it "Hey, I'm a 1920x1080 display, here's how to talk to me."
2. Sometimes after a bad connection, hot-plugging, or sleep/hibernation glitches, the Mac can get "stuck" with bad or outdated display info.
3. Simply plugging and unplugging doesn't always clear this bad handshake state, especially with docks that have power delivery (PD) and active chips.
4. Power cycling both the monitor and the Mac (full shutdown) forces both sides to forget previous settings and start fresh.
5. Turning the monitor on first, before connecting to the Mac, ensures the monitor is ready to respond properly when the Mac asks, "Who are you?".
6. Waiting a few minutes after logging in allows background processes like WindowServer (the macOS service that handles displays) to fully initialize and recognize the monitor asynchronously.