Many WordPress developers and designers use bbPres as a means for public support.

It’s a nice approach to handle support requests because the replies are public and can be found by other users. It adds a little bit of extra step to the customer to sign up and post.

Also it’s inconvenient to paste login information in such a forum.

When I started Orbisius I installed that software and it worked well.

In the last few years I noticed that lots of spammers started signing up just to get a backlink to their sites or products without being a client at all. You can use these snippets in functions.php or in a custom plugin.

How to Make bbPress Author Page not Indexable

The first approach was to make the author page not indexable.

That approach will automatically lose lots of pages as each author page is a separate indexable page that may help with SEO.

<?php

// Spammers are getting very annoying
if (!empty($_SERVER['REQUEST_URI']) && (strpos($_SERVER['REQUEST_URI'], '/forums/users/')) !== false) {
	header("X-Robots-Tag: noindex, nofollow, noarchive, nosnippet", true);
}

How to Remove Author Bio/Description using bbPress filters/Hooks

The next approach was to remove the author link and bio/description from the author page.

<?php

add_action('bbp_get_displayed_user_field', 'orb_fix_post_6433_no_forum_bio', 20, 3);

// Lots of spammers are putting their links and info in their bio so empty those.
// file: plugins/bbpress/templates/default/bbpress/user-profile.php
function orb_fix_post_6433_no_forum_bio($val, $field, $filter) {
	$skip_fields_arr = [ 'user_url', 'description', ];

	if (in_array($field, $skip_fields_arr)) {
			return '';
	}

	return $val;
}

This should reduce the traffic to your server. I suspect that even if the link is nofollow some search engines will still follow them.
I also suspect that having such links could affect your site's reputation in a negative way.