Hey Filipe,
I was looking into this as well. From what I can tell, IBM hasn't announced a replacement for the v20.12.x RPA Developer certification yet, or provided a date for a new exam.
IBM does have updated RPA 23.0.x training and learning paths available, so the product and training are still being actively supported. It looks like the certification just hasn't caught up with the newer versions yet.
Hopefully IBM can confirm whether a new certification is planned and what the timeline might be.