[Bug]: Pixelfed don't show some comments

Description

Pixelfed don't show some comments Pixelfed don't show comments 3-rd and more levels, answers to comments to comments. They exist, are preserved, are properly federated with other instances. They can be accessed by direct link from notifications, but they do not appear under the Pixelfed post, and home feed. But I see normally all this comments in Misskey, Friendica etc. For sample see comments to this post in Pixelfed https://pixelfed.de/p/Konstantin/817403182377918593 and in Misskey https://plasmatrap.com/notes/a6l1yhk8aj and in Friendica https://libranet.de/display/8ef473fd-16a4e1a966e32025-f5e7b574

Steps to reproduce

1. A subscriber comments on my post.
2. I reply to him.
3. He comments on my reply.
4. I only see his comment and my reply below the post. His comment on my reply and other comments in the thread are not shown.

Pixelfed version

v0.12.5

Acknowledgements

Yes