The spoiler tag doesn’t seem to work correctly on the mobile app (Jerboa):

Spoiler feature appears to be Non-Functional on the mobile applications Mlem and Jerboa

Don’t worry, we won’t really need a spoiler tag for the foreseeable future.

Working in the web browser - nice idea though.

FYI spoiler tags don’t work on the Jerboa app.

It works on this page but not in the feed, there I saw the raw code instead (when viewing it in a mobile browser)

When I open the post it shows the spoiler, but just browsing through my feed it showed “Lemmy wins” in the preview. Using the website on mobile

No dice on kbin either. Think its more the platform doesn’t know what the tag is though.