Typically “rebalancing” changes are noted in the Release Notes, but the only change noted for Version 19 regarding emblem drop rate is an increase for some of the loot sources:
It’d be worth opening more than a handful of Monster and Raid Chests before evaluating whether the drop rate on those has changed.
If you’d like to track your results and post them on the forum to compare with others, there’s a thread that’s been tracking drop rates, both from Version 18, and now Version 19, so they can be compared: