Hi.

1. Turn on Syntax Highlighting.
2. Open wikitext on some page.
3. Enter some words, at least two.
4. Just after the last click + as shift-= or * as shift-8.
5. The last word disappears, there is just a symbol.

Any use of keyboard, even minimal, avoids the problem - for example, after the word click space, delete, comma will give the expected result.
The problem does not happen with the first word in the line, so my guess - something wrong with regular expressions.
Checked a couple of browsers, it's on Android 6.0 at least.