Based on the error messages, this was likely caused by unpairing. Could you check if your PC is paired with the HoloLens device?

Additionally, please try using Visual Studio 2022 instead of 2019 version, which can also cause issues while deploying. See recommended VS version and the necessary workloads on it - https://learn.microsoft.com/en-us/windows/mixed-reality/develop/install-the-tools#installation-checklist.