Missing feature is from

bootstrap-vue

Docs

https://bootstrap-vue.org/docs/components/popover#variants-and-custom-class

Describe the missing feature

Bootstrap-Vue enabled setting variants for BTooltip and BPopover - we've implemented the variant prop in the same way the BSV did, but from what I can tell, BSV implemented the CSS - neither BS4 or BS5 has the concept of variants for tooltips and popovers. So if we want to implement this, we should port the SCSS, otherwise we should fully deprecated it.