Selfhosted Piped and Cloudflare Zerotrust?

Cheers! I’m hoping to self-host Piped but I’m using cloudflare tunnels / Zerotrust to configure my containers public access (awful ISP CGNAT means this is the best way for my usecase). I’ve followed the docs https://docs.piped.video/docs/self-hosting/#docker-compose-nginx-aio-script and have configured a public hostname pointing to the nginx container’s port configured in the compose.yml file – but while I can access the frontend the backend/proxy seem to not be able to connect. I found this github issue discussing it https://github.com/TeamPiped/Piped/issues/2600 but even if I add CNAME references manually (though they are now generally handled through Zerotrust) I can’t seem to get things to work. The “Trending” page seems to be continually loading, and the logs for piped-backend show

org.postgresql.util.PSQLException: Connection to postgres:5432 refused. Check that the hostname and port are correct and that the postmaster is accepting TCP/IP connections.
	at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:346)
	at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:54)
	at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:273)
	at org.postgresql.Driver.makeConnection(Driver.java:446)
	at org.postgresql.Driver.connect(Driver.java:298)
	at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:683)
	at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:230)
	at me.kavin.piped.utils.LiquibaseHelper.init(LiquibaseHelper.java:32)
	at me.kavin.piped.Main.main(Main.java:82)
Caused by: java.net.ConnectException: Connection refused
	at java.base/sun.nio.ch.Net.pollConnect(Native Method)
	at java.base/sun.nio.ch.Net.pollConnectNow(Net.java:682)
	at java.base/sun.nio.ch.NioSocketImpl.timedFinishConnect(NioSocketImpl.java:542)
	at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:592)
	at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
	at java.base/java.net.Socket.connect(Socket.java:757)
	at org.postgresql.core.PGStream.createSocket(PGStream.java:243)
	at org.postgresql.core.PGStream.<init>(PGStream.java:98)
	at org.postgresql.core.v3.ConnectionFactoryImpl.tryConnect(ConnectionFactoryImpl.java:136)
	at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:262)

Has anyone had luck hosting Piped using cloudflare tunnels and can point me in the right direction?