> apart from which website you logged on and when
Which is the whole damned problem, obviously.
> This quite literally the standard of Signal [1].
Yes, Signal is weak in a similar way. Although there is a difference between having to set up a bunch of wiretapping to do traffic analysis, and having the information handed to you on a plate.
> And this is of course assuming the worst from the national id implementation; any sensible law would require the id provider to delete all information as soon as the login is complete.
Assumptions that laws will be followed are out of order. Yes, you have the laws. Yes, you punish violations. But you still deal with the fact that violations will happen.