Use of callout's type `tip` is not possible in PDF.  The `\faLightbulbO` command which is used  in the `tcolorbox` defintion is a  fontawesome's package command but with the fontawesome5 package the `\faLightbulb[regular]` command must be used.
2021-11-14T17:21:47Z
epabion
closed
Rendering Tip style callout in PDF
https://github.com/quarto-dev/quarto-cli/issues/183