display_name error in author template after update to v.3.5.12

We experienced something odd after updating to v.3.5.12. On all of our author pages, the name of the author was replaced by the name of the site administrator.

The template code for the author’s name in the template code of our author.php is:
echo get_the_author_meta( 'display_name' );

Everything is normal again after rolling back to v.3.5.11, but we’d love to know what went wrong or what we might need to do for our author.php to keep it working together well with co-author plus.

Here is a dropbox link to our author.php file: https://www.dropbox.com/scl/fi/bmo5n1sk2c7oaf89mdfhn/author.php.zip?rlkey=xmib6kv3hcca32gngupgwz4dk&dl=0

And here is an example of the author.php behaving properly under v.3.5.11: https://opensiddur.org/profile/lise-tarlau/