Really the problem boils down to:

“I don’t want to maintain a custom fork with my fix” - valid sure, if you are not sure if your fix is the best solution for it, and would like the general community to comment (i think the problem here is that iterating on a fork is generally difficult to discover and work on)

“I really want everyone to have the benefit of this fix” - Could be interpreted as wanting the "fame" of authorship or participation in a large open source repo, otherwise just sharing the fix and letting whoever needs it is enough tbrh.

“I don’t know what the fix is, but there is a bug here and the core team should fix it” - would be a user support issue.