In applications/core/dev/html/front/sharelinks/reddit.phtml, line 4 is missing the closing brace on the language tag:

<span class="ipsInvisible">{lang="reddit_text"</span>

It should be {lang="reddit_text"}. As a result every Share menu outputs the literal text {lang="reddit_text" inside the visually hidden span, so screen readers announce the Reddit share link as that string instead of "Share on Reddit". The tooltip on line 2 is correct. Confirmed this on 5.0.20 with the default theme.

Fixed in 5.1 by the look of it

It does not surprise me yall are ahead of this! Hope all is well Marc!