Among the many databases FireDAC supports, one commonly used by our customers is Firebird (the open source spin-off of InterBase). FireDAC used to have a single driver for Firebird and InterBase, given they still have a significant degree of compatibility after many years, but more recently the R&D team split it in two separate drivers, with more specific configuration settings and defaults.
In RAD Studio 10.3 we introduced support for Firebird 3.0, including some specific new features like new statistics features in gbak output, changes in isc_database_info() call, few FB$OUT package, local connections, and online validation.
In the recent RAD Studio 10.3.1, we've added a couple of additional Firebird 3.0 features:
Support for wire compression in Firebird 3.0.4 (via the isc_dpb_config and isc_spb_config settings), a feature mentioned at https://stackoverflow.com/questions/53938537/how-to-enable-wirecompression-on-firebird-3-0
We have done other improvements in FireDAC overall, but in terms of actual new features this was a limited but important focus area, for all of our customers who use Firebird.