One week later the exact same problem happened again, but this time it resolved when I disconnected from a VPN. (Mind you, when I first had the problem, I was not connected to a VPN, so that's not the extent of the issue.)

Thanks but no. That wrapper @CodableConfiguration is used for AttributedStrings with custom attributes. The attribute assigned above (imageURL) is a first-party attribute from Apple's Foundation framework, so no special coding process should be needed. (In my app, I actually am using custom attributes, so I was using @CodableConfiguration when I first came across the error, and I initially thought that might be the source of the problem — but in the process of debugging the error, I switched to a standard attribute and the problem persists.