Give it time, it can still grow, but that's not a Birkin. Looks like a Scindapsus.

Whoops, you're right. I keep mixing up Birkin and Brandtianum.

Look up some information on wet stick propagation. It may be better off sitting on moist sphagnum moss in a humidity dome or ziploc baggie. I think it can grow another leaf but it will take some time.

Also, I got some cuttings from brandtianum last year and they put out all tiny leaves for a while. I finally got one normal-sized leaf after about 5 months. I have the cuttings under a cloche.

Good idea, I was considering wet stick, but wasn't sure if it would be very successful with a philodendron.