This page redirects to an external site: https://developer.wordpress.org/reference/functions/is_blog_user/
Use is_user_member_of_blog() instead.
Checks to see if the current logged in user is a member of the blog specified.
<code style="color: #000000"><span style="color: #0000BB"><?php is_blog_user</span><span style="color: #007700">(</span><span style="color: #0000BB">$blog_id</span><span style="color: #007700">) </span><span style="color: #0000BB">?></span></code>
<code style="color: #000000"><span style="color: #0000BB"><?php
</span><span style="color: #007700">If (</span><span style="color: #0000BB">is_blog_user</span><span style="color: #007700">()) {
</span><span style="color: #FF8000">//user is a member of this blog
</span><span style="color: #007700">}
</span><span style="color: #0000BB">?></span></code>