Looks like there is no problem with default theme.
Theme causing problems is Newspaper 11
After switching off all of these plugins problem still exists, no <span><span> in username/avatar and no link when user is logged out.
bbp profile information
bbp User Ranking
bbPress Login Register Links On Forum Topic Pages
bbPress Messages
bbPress WP Tweaks
Active Style Pack, logged in:
<div class="bbp-reply-author">
<a href="(....)" title="Zobacz profil: uzytkownik421" class="bbp-author-link">
<span class="bbp-author-avatar">
<img alt="" src="(....)" srcset="(....)" class="avatar avatar-80 photo" loading="lazy" width="80" height="80">
</span>
<span class="bbp-author-name">
uzytkownik421
</span>
</a>
Active Style Pack, logged out:
<div class="bbp-reply-author">
<img alt="" src="(....)" srcset="(....)" class="avatar avatar-80 photo" loading="lazy" width="80" height="80">
uzytkownik421
Looks like something replaces 'function bbp_get_reply_author_link' bbpress/includes/replies/template.php
