Comment form gets display:none; on node page for reply

Problem/Motivation

When a visitor press the link for replying to a comment, a display:none is added to the comment field on the reply page. The added CSS vanishes when I deactivate Comment Notify.

Steps to reproduce

Visit https://www.voffor.se/avsnitt/8-kalle-anka-och-hans-vanner-onskar-god-jul and press "Besvara" (Swedish for "reply"). A new page is loaded, where comment-field isn't visible.

I can't understand why this is happening, I've checked the settings for both Comments, the node itself and Comment notify, but nothing seems to prevent this from happening (except deactivating the module).

This happens in both my custom theme as well as in Olivero.

Please, help.

// Adam