If you are talking about data missing from the `text` column, for some reason it disappears after you read a message. The content is stored in a binary blob in a different column, which I parse like this: https://github.com/ReagentX/imessage-exporter/blob/c73bc4d66...
I drilled keybr from 30wpm to 110 several years ago and still come back every few days to practice. It is a great tool. I sometimes use it to "study" documentation by pasting it in as a custom prompt.
This feels like a case where it'd be good if Apple had two different messages, one for SMS filters which have a ILMessageFilterExtensionNetworkURL configured (which should get the scary message you saw) and one for those that don't (which are sandboxed to be purely device-local).
That said, Apple doesn't really handle the case of permissions changing with an app update very well, so launching your app purely device-local then updating to add something server-side a year later would probably let you get around that.
This app seems to not have the key that'd indicate it's capable of sending anything to a server: https://github.com/afterxleep/Bouncer/blob/master/Bouncer/In... (though, you know, that assumes that the build on the App Store is directly from the source we can see...)
It's a boilerplate warning that applies to the maximum possible amount of data-collection that could be happening. The app says it doesn't collect anything, and its source on GitHub supports that claim... but a SMS app theoretically could and so Apple warns you of the worst case.
> I would buy clothes with no distinctive marks if I could find them.
Find a local tailor. Pick the fabrics you want from a catalog. Get your clothes made for your body while supporting someone's small business and artistic craft.
They're almost always sewn on as pre-made patches nowadays, at least in my area. I will forgive the clothier a printed patch but yes the fabric manufacturer's must be woven.