None whatsoever that I have found as yet. However, the install did take a very long time for a 'point' update & so I suspect that much was going on 'under the hood', possibly firmware update given the re-booting and faffing about that was going on. I did two update installs: one for the 2TB Apple primary boot & another for my 256GB Alt Boot NVMe. Both the same.
If this is anything like similar updates in the past, perhaps 10.15.3 might set the stage for other App store updates in the near future, eg, FCPX, Pro Apps support updates, Logic etc? We'll see.
Edit: also see
https://eclecticlight.co/2020/01/29/what-changed-in-the-catalina-10-15-3-update/