One or more "See Also" fields of the bugzilla (top-right side) are useful points of integration. Example: link, see the screenshot below.
Unfortunately the opposite way does not work yet: Phabricator won't display bugzilla links. But if you use the "BUG:____" lines in your git commit messages they at least appear in summaries of Differential revisions (example).
Thanks to Ben who tirelessly enabled the links.
PS: These weeks mark end of my 13rd year in KDE!