Proposed to be included in WordPress 6.0 is a new feature to generate and use webp images by default. Specifically, when an image is uploaded, a WebP version of every image subsize is created. According to
the proposal, one downside is that generating WebP versions along with the original JPEGs will "use an additional ~70% of the storage space to store both file types." Although this is hugely beneficial to most websites and, more importantly, their visitors, some site owners may not be immediately able to increase the size of their storage to accommodate the additional files. For more information, see the proposal or
the Trac ticket.
To help site owners manage the transition, this plugin adds a setting under Settings -> Media to either enable or disable WebP creation on the initial upload of JPEGs. For Multisite installations, the plugin can be activated network-wide or on individual sites.
*** 2022-07-22 UPDATE ***
Although the original implementation was not merged in 6.0 due to community feedback, changeset 53751(
https://core.trac.wordpress.org/changeset/53751) merged an updated implementation that addresses some(but not all) concerns from the community. This merge will be part of the 6.1 release, unless further changes are needed. Some site owners may not be able to immediately cope with doubling their required storage allotment with their host, so the original goal of this plugin remains. The code has been updated to disable WebP creation on upload globally. There is a new ticket discussing the possibility of making this feature into a setting(see
https://core.trac.wordpress.org/ticket/56263). However, given WordPress's core philosphy of "Decisions, Not Options", it's unlikely to proceed.