That's our experience as well. The change was made well prior to 2019. We still get OBC back, and the $100 down is our deposit. Still seems like a good deal to me. Here's a quote from a FCC letter from 2015:
Effective Date: May 6, 2015
Book By Date: May 4, 2017
This letter confirms that we have received payment for deposit* in the amount of 100.00 USD towards a future cruise with Princess.
Upon making your new booking, the appropriate shipboard credit will be applied.*
Future Cruise Length Per Person Shipboard Credit*
17 + Days $125 Inside, $125 Outside, $150 Balcony, $150 Suite
11 - 16 Days $75 Inside, $75 Outside, $100 Balcony, $100 Suite
7 - 10 Days $25 Inside, $25 Outside, $50 Balcony, $50 Suite
3 - 6 Days $15 Inside, $15 Outside, $25 Balcony, $25 Suite