I have noticed this behaviour since yesterday, but perhaps it was happening already before then.
To reproduce, on a Mac:
1. Open an SSH session, any will do.
2. Type some string with word breaks, for example, "aaa/bbb/ccc"
3. Press Cmd+Left. Instead of moving the cursor to the beginning of "ccc" which is what used to happen, instead "D" is appended.
4. Go to the beginning of the line. Press Cmd+Right. "C" is inserted instead of moving the cursor to the end of "aaa".
In your bug report guide you mention sending a recording of the session to facilitate debugging, but I could not find instructions on how to do this.
Thanks!
Eric