RC, JFG, and LFM acknowledge support from grant PID2020-114461GB-I00 and the "Center of Excellence Severo Ochoa" award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709), funded by MCIN/ AEI /10.13039/501100011033. RC is also supported by the predoctoral grant PRE2018-085518, funded by MCIN/AEI/ 10.13039/501100011033 and by ESF Investing in your future. This work is also partially supported by grants R18-RT-3082 (IAA4SKA) and P20-00880, funded by the Economic Transformation, Industry, Knowledge and Universities Council of the Regional Government of Andalusia and the European Regional Development Fund from the European Union.

OHPNe are considered nascent planetary nebulae (PNe). In fact, only 6 OHPNe are known to date. We processed ~300 h of radio interferometric data, and identified 4 new OHPNe candidates. Also, we show the unexpected C-rich nature of a central star that ejected an O-rich (C/O ~0.3) circumstellar nebula. This source is the OHPN Vy 2-2. We use CARMENES spectrum to confirm its nature as a nascent PN.