Reads on the Dictionary are not locked with the write operations, which is not supported.
Suggestion is to use a ConcurrentDictionary and remove some of the locks, or use a ReaderWriterLockSlim.

https://github.com/dotnet/efcore/blob/main/src/Microsoft.Data.Sqlite.Core/SqliteConnectionFactory.cs#L53

c.f. Dictionary source that is can throw an exception if the collection was changed while reads occur.
https://source.dot.net/#System.Private.CoreLib/Dictionary.cs,398