Can't install Webp extension for Joomla 4

Can't install Webp extension for Joomla 4

Hi,
I'm trying to install Webp plugin for Joomla4, (two sites, v4.1.2 and v4.1.5). After installing from your site, there is only one plugin added (system plugin). The plugin for converting images is not installed. If I try web installation from Joomla admin panel I get this error:
Unable to detect manifest file.