There's a comment that events which are annotations (ie, reactions) or replacements (ie, edits) should not have bundled aggregations included with them. This behavior was regressed in #11660 as it causes the check for the event type to be skipped when calculating edits:

Subsequently this was also made buggier for threads in #11752 for similar reasons.

(Note that the behavior about whether these events can have relations to them or not, and whether those should be bundled, isn't clearly defined.)

Noticed in #12273.