I have just found this information that WebP files are dangerous. Delete them all without delay. More information is available here, and here.
IMG source - Chromium.Googlesource.com
As is my wont and usual practice, upon discovering this information I have posted this notification so that you can undertake your own analysis and decisions as to appropriate actions, and cannot confirm it's veracity and effectiveness of proposed solutions for you. From my initial glance at this vulnerability it appears confined to a sandboxed arena. However, any additional exploit that can escape the sandbox would make it extremely dangerous, from my layman's understanding. Please take appropriate action at your earliest convenience.
I'm deleting all WebP files and refraining from any further use of them to the extent I can manage.