For what it's worth, they don't retain any of that metadata. This has been tested in court:

> We’ve designed the Signal service to minimize the data we retain about Signal users, so the only information we can produce in response to a request like this is the date and time a user registered with Signal and the last date of a user’s connectivity to the Signal service.

https://signal.org/bigbrother/eastern-virginia-grand-jury/

This was even before sealed sender, so if anything my confidence in the Signal Foundation has only increased.