https://github.com/serilog/serilog/blob/7f3a5bfec73dba1c3b29780b85a53b0fe2f7c52b/src/Serilog/Events/LogEventLevel.cs

Switch Off was introduced in nblumhardt@9b92c29 to resolve #1684

However LogEventLevel was not updated to introduce this level.

This causes bug serilog/serilog-settings-configuration#461 in serilog-settings-configuration, where log level Off can not be read from configuration (appsettings.json for example). Bug is caused by this line, which parses log level into LogEventLevel enum.