Found one old forum entries about Bevelbuttons:
https://forum.xojo.com/t/mac-bevelbuttons-turning-blue/66488/3
The hint of interest can be found on archive.org now:
“Archive_org/Apple Developer/Human Interface Guidelines/Bevel Buttons”
https://web.archive.org/web/20211019072439/https://developer.apple.com/design/human-interface-guidelines/macos/buttons/bevel-buttons/
Mainly, this link says: “Avoid Bevel buttons”