I think it should be taught in 4th or 5th grade for a few weeks, maybe even older in middle school instead.
I learned it in 3rd grade while it was still challenging to copy letters. Maybe because I was a year ahead it might have been harder for me. In 6th grade they timed our ability to write what was dictated to us, and just those two weeks of practice I became much faster at writing. Huge help in school for taking notes as I got older.
Children today might not use cursive regularly, but I think they should get a few weeks of learning it so they can read it, and for those students who take to it well, it usually is faster to write in cursive than to print.
Don’t you think if you had never seen cursive before, and you are a teen or an adult, and someone spent a few days going over the basics, you would easily be able to read it, even if it was a little slow, stumbling over remembering the capital I or G. In English we can read a sentence full of typos and letters missing and still read it fairly easily and fast.