Description: We're suddenly seeing a large number of posts with titles containing invalid characters such as line-breaks, starting on approximately Wed Feb 14 20:19:16 2024 UTC. We've had to start blocking these posts, as they're causing a wide variety of errors with our bot; other bots/scripts are likely to be affected too, as no previous posts we can find have ever had multi-line titles like this.

Platform and version: Reddit Android App, version 2024.07.0. So far, user reports we've gotten have only been from users of the latest release (2024.07.0) of the Reddit app on Android, so most likely the bug was introduced in this version; we don't know that it doesn't also affect iOS, only that nobody has yet reported it there.

Steps to reproduce: So far, all reports have stated that the line-break insertion happened due to the user copy-and-pasting the title from either a notes app, or from a previous post. The app might be failing to filter any invalid characters only on paste. All of the posts noted so far had the invalid characters at the very end of the title (followed only by whitespace), which may also be significant.

Expected functionality: Reddit should be stripping invalid characters/line-breaks, as it apparently has been doing for years. Line-breaks in post titles does not appear to be an intended or sensible feature.