The logo has 800x264px size. It is assigned to the login page in Atum template:
And here is the result:
The script attempts to display 800x264, but the image is too big and deformed.
I played in browser console and set the width to 300px and it looks nice:
This issue appeared after upgrading from Joomla 4.2.6 to 4.2.7.
#39766 closing as already fixed
#39766 closing as already fixed