Why is an argument of onChange nested in … in Gutenberg custom block RichText?

It’s because you have multiline: true, as documented:

By default, a line break will be inserted on Enter. If the editable
field can contain multiple paragraphs, this property can be set to
create new paragraphs on Enter.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)