I guess because it explicitly displays the target comment, but, if you click on parent comment or something like that, also loads the parents comments, with all child comments - including the original one, despite the original one still being displayed. I have the same issue, and it’s Eternity exclusive. I hope it will be fixed soon.
He survived KDE and other heavy DEs. A normal Arch users habitat is a plain WM, ideally based on Wayland, so sway/Hyprland/qtile. He will be fine.