From dotnet/coreclr#17076

https://github.com/dotnet/corefx/blob/619dbe6503a2de2afa27122cb34716d9ff6906ff/src/System.Data.SqlClient/src/System/Data/SqlClient/SqlConnectionString.cs#L488-L492. cc: @saurabh500. There's no synchronization whatsoever (no locks, no interlockeds, no volatiles, etc.) used in lazily initializing this dictionary. It's possible that could be an issue on some hardware.