serebit I installed EndeavourOS with Budgie and was immediately greeted by a Budgie configuration that I hadn't seen since around 2017 (anyone else remember the top panel?). This led many to the conclusion that Solus had the best configuration for Budgie and that other distributions were lagging behind, which shouldn't have been the case.
I checked a number of Budgie implementations (Ubuntu Budgie, Gecko, openSUSE and so on) in Gnome Boxes yesterday and this morning. All seem to be following this pattern.
serebit [T]he Budgie defaults on Solus are custom—the defaults in the upstream repository were years old due to having never been updated to fit with the more modern look of Solus's Budgie configuration.
Thanks for pointing that out. I had assumed that other implementations were flawed/inexpert/clumsy. I did not understand that the issue arose out of different repositories, upstream/downstream failures. I hope that splitting off the Budgie project as a standalone will eventually result in common implementation across distros.