Hello,
Actually, the Aspasia template is made of the Helix3 framework. And as you know Helix3 framework gets Joomla 4 compatibility update, so it has to be changed a lot to adapt to the new Joomla version. We are updating all of our Helix3 based templates too. But the Aspasia template has not gotten the compatibility update yet.
Hence, it's a cordial request to you that kindly roll back to your last working backed-up version of your site. I hope you have one? Kindly do not update your Helix3 system plugin until there is no template update available itself.
Thanks for your patience!
Best Regards