I have upgraded my Unity from version 2022 to 2023 and I am facing issues similar to the screenshot. Both MLAgents and Santis packages were complaining around the Google Protobuf. When I have updated the Sentis to the latest 1.0.5.pre.1 the problem has gone for it. Unfortunately with the MLAgent’s I am already in the latest version with the 3.0.0.exp.1
I have cleared the Library folder several times as well as I have reinstalled and upgraded packages related to the errors like Burst, Mathematics, ague and test-framework