When there is a "|" inside the nowiki tag in the text inside a table cell, this "|" is still recognized as part of the wiki markup
{| class="standard" | <code><nowiki>{{ACB|PG}}</nowiki></code> |}
in the preview in the editor-2017 it looks this (there is no code tag and the second "|" is recognized as part of the table cell )
PG}}
but in the preview in the editor-2010 and after saving it can be seen normally
{{ACB|PG}}
https://ru.wikipedia.org/wiki/Шаблон:ACB/doc