Hi
Thanks for contacting us. You can follow this link below:
https://www.joomshaper.com/documentation/sp-page-builder/how-to-tips#how-can-i-add-support-to-webp-files
If in your Joomla Media - you can upload .webp - it's OK, but it doesn't mean that all extensions support that format. SP Page Builder can, but about others, I cannot promise you. Then use .jpg for them.
If you still cannot use .webp in Joomla > Content > Media (J!Core):
make research on forum.joomla.org
And ask Hosting support, maybe there is missing PHP extension for that format
We cannot change your Joomla behavior.
You can also follow this forum post below:
https://www.joomshaper.com/supports/forums/question/10988?order=newest
-Regards.