@kuba you're doing the right thing! Or at least you're doing what should produce the result you want according to the default configuration of less(1).
However you say you're invoking less "indirectly" with journalctl; do you mean you're running journalctl ... | less, or just running journalctl and letting it invoke less(1) itself as the default pager? If the latter, it's useful to know that systemd invokes less with some quite non-default options!