Apparently, when viewing talk pages in the mobile version (or the app), potential TemplateStyles will not be applied to the "overlays container", which leads to rather strange outcomes in some cases. Obviously, there will always be templates on talk pages, so TemplateStyles must be applied also in the mobile view (and not just when continuing with "read as wiki page").
Random example: [[ https://de.m.wikipedia.org/wiki/Wikipedia_Diskussion:Redaktion_Musik#AfM%3A_Sting_%E2%80%93_%E2%80%9EBrand_New_Day%E2%80%9C | here the table is broken]] because of missing TemplateStyles
# Developer notes
The talk overlay element with classes "content talk-section" needs to also add the class mw-parser-output
# QA steps
[x] Visit https://en.m.wikipedia.beta.wmflabs.org/wiki/Talk:Test#Template_styles on mobile
[x] Verify the box is styled and floated to the right.