Joomla 4.1 introduced child templates, therefore assets such as CSS and JS have been primarily moved to the folder media/templates/site/name_of_my_template. Eventually I do not care very much about this, since I do not use child templates. I just wanted to bring to your attention, that the «J51 - Kaylee - Joomla 4» template (Version: 1.0.5) does not yet respect this new storage location.
Kind regards
Chris