I call it this every chance I get because its like nails on a chalkboard to many DBAs.
edit: huh. both my clients have spoiler tags, but both are apparently broken. I can't decipher what Lemmy wants me to do for the markdown to fix it, probably the client not displaying it right.
edit 2: yeah, it looks correct on the default browser interface, but both apps I use (Boost for Lemmy and Eternity) fail to render a spoiler.
Your spoiler tag works fine on the web client. That is the supported way to do spoilers on Lemmy. However, Sync, if you use that doesn't support Lemmy spoilers and only supports reddit spoilers. Unfortunately no matter what spoiler method you use, it will not work for someone, somewhere. There is no unified spoiler markup across the fediverse, but there really should be.