Why does Word take plain text as headings?

Question

Windows

Headings are indicated, between them the text is normal. The program itself clings to the headings, but if I insert a table of contents, then plain text gets into it. I think this screenshot will clearly explain everything. Headings on the left, and an automatically generated table of contents on the right.
I have already dug up the settings for the table of contents, although there are not particularly settings there. I have not the slightest idea about the reasons for this miracle.

Answer 1

If the text is in the table of contents, then it is marked appropriately. You can try to select this plain text and reset the styles for it (select the first item in the Styles panel - Clear All).