the_content() printing site title after page/post title and before its content

My pages are all showing the Site Title (from the Customizer) after the page or post title and before the "body" of the post. Troubleshooting by injecting lines of text to print before and after WordPress code narrows the source down to the the_content() call within the page template.

Here’s how the_content is called:

        ...         </header><!-- .entry-header -->          <div class="content entry-content">             <?php the_content(                 // Translators: %s: Name of current post. Only visible to screen readers.                 sprintf( esc_html__( 'Continue reading %s', 'bulmapress' ), '<span class="screen-reader-text">' . the_title( '', '', false ) . '</span>' )             );              wp_link_pages( array(                 'before' => '<div class="page-links">' . esc_html__( 'Pages:', 'bulmapress' ),                 'after'  => '</div>',                 ) );                 ?>         </div><!-- .entry-content -->          <footer class="content entry-footer">         ... 

I’m a bit baffled because post_template.php where the_content() and get_the_content() are defined is a WordPress /includes file, not a parent theme file.

Should I be looking for some filter that’s been defined in the theme? TIA