I did some additional testing on two different Discourse deployments. and here’s the combination of settings that causes the component to cause issues on mobile.
- Included in theme, Mobile thumbnails setting on. Thumbnail displayed ok.
- Included in theme, Mobile thumbnails setting off. topic list is all funky.
Discourse version: v3.5.0 (05a3040066)
Topic Thumbnails: latest as of Sep 15 2025.