There is no changelog although I assume that this contains the updated microcode to guard against the Spectre flaw. I haven't tried it yet because I don't beta test firmware updates on production machines especially without changelogs posted.
Have used the advice posted in this thread to update to 5.63.3144. I ended up flashing twice; once to go to 5.62, then again to 5.63 when I was confident in the procedure. I have now encrypted my volumes with Bitlocker as I originally set out. Thank ...