Luxon's `DateTime.fromRFC2822() has quadratic (N^2) complexity on some specific inputs. This causes a noticeable slowdown for inputs with lengths above 10k characters. Users providing untrusted data to this method are therefore vulnerable to (Re)DoS attacks.
This is the same bug as Moment's https://github.com/moment/moment/security/advisories/GHSA-wc69-rhjr-hc9g
Limit the length of the input.
There is an excellent writeup of the same issue in Moment: https://github.com/moment/moment/pull/6015#issuecomment-1152961973
DateTime.fromRFC2822("(".repeat(500000))
takes a couple minutes to complete.