With the recent Thulean* comment spam attacks, mods have dutifully deleted the offending comments, but Thunder still renders the deleted comments.
Connect seems to have the same bug
Voyager and Jerboa show the comments as deleted
Examples:
https://startrek.website/post/8228446
Thanks for mentioning this issue! I believe this has already been fixed in the latest nightly build v0.3.0-1.
The fix is not yet on the general release build yet (v0.2.9) but should come eventually when v0.3.0 is near completion. As a temporary measure, you can block the user and the corresponding comments should be gone!