'
These are usually seen on posts older than the 2017 system update and detail functions from the old system deemed not worthy of spending time to update so they'll work w/ the new?
Common examples are Emoticon/Graemlins, Text Bolding, Underlines etc...your example maybe a Font Size change from standard and code text now shows instead of requested function?
One of the most common was
which if input w/ the old system now shows as [img]<<GRAEMLIN_URL>>/beers.gif[/img]
A few common fixes would make reading old posts a whole lot easier but it's hard to complain as I don't want the job nor have any idea how to fix it anyway plus most importantly, SYC still rocks in most other ways!
~ Pete