Gutenberg Heading forces HTML anchor text

Before WP 5.9, I could leave the anchor text of a Gutenberg Heading block empty. That way I could prevent some headings from appearing in a Table of Contents.

After updating to WP 5.9, the HTML Anchor field is automatically filled in. I can edit it, but cannot empty the field.

Can that behavior be reverted? If not, how can I prevent certain headings from appearing in (automatically created) TOCs?

• This topic was modified 2 years, 2 months ago by dutchintouch.