If a footnote text includes right brackets - ] - the first one will match with the "footnote:[" markup of asciidoc, provoking an early interruption of the footnote, and pushing back the end of the footnote text in the main text.

Example, using test.docx, and running:
pandoc -f docx -t asciidoc test.docx
produces the following output:
textfootnote:[[…] footnote]

Escaping the inner right brackets should fix the issue (cf. asciidoctor/asciidoctor#2495 (comment)), producing this output instead:
textfootnote:[[…\] footnote]

I used Pandoc v2.5 for the test, but it should still apply to the latest version from my understanding of the AsciiDoc writer code.