Immigracion check in upon departure?

I left ZIH in December. There was no migración check out.

I left ZIH in March, there was a migration checkout.

The airline printed in big letters on my boarding pass “MIGRACIÓN” and highlighted it in yellow.

Migración had me sign their book, photocopied both sides of my RP card and gave it to me to hand in as the plane was boarding.

The process at migración took maybe five minutes.