What to do when you find a bug?

I think i've found a bug, but i'm not sure the protocol for where to submit it.

The bug:

This comment: https://old.lemmy.ca/comment/3118239

• clicking "load more comments" shows nothing.
• clicking "view the rest of the comments" shows comments on post, but without this reply

For the regular view: https://lemmy.ca/comment/3118239)

• clicking "show context" shows a sibling comment
• clicking "View all comments", shows all comments but either my comment or the sibling comment.
• clicking "1 more reply" returns nothing

I think the parent comment (and replies to my comment have been deleted. Maybe this is intentional behaviour

Actually this might be the bug: https://github.com/LemmyNet/lemmy/issues/3886