Over-the-counter and exchange conventions append a fifth character to signal status: a trailing Q has long meant bankruptcy proceedings, D a reverse-split, V when-issued trading, and F or Y patterns for foreign issues and adr lines. Quote vendors vary in how they display these, and some venues have moved to flags rather than letters.
Whatever the display, the underlying point is that the ticker-symbol carries status information, and a symbol change notice is worth reading rather than ignoring as cosmetic.
Example: XYZ files for chapter-11 and quotes begin appearing as XYZQ on the over-the-counter market. The share count and the claim are unchanged; only the identifier and the venue moved.
Related: ticker-symbol, chapter-11, delisting, otc-markets, reverse-split