What happened:
Version 1.0.0-1.1 of firewalld breaks inter-container networking, at least for Mastodon's docker-compose.yml.

Container mastodon_streaming_1 shows these errors repeatedly while trying to connect to the mastodon_redis_1 container:

WARN Starting worker 50 
WARN Worker 50 now listening on 0.0.0.0:4000 
ERR! Error: Redis connection to mastodon_redis_1:6379 failed - connect EHOSTUNREACH 172.24.0.3:6379 
WARN Worker 50 exiting

What you expected to happen:
Containers can still connect to each other.

How to reproduce it (as minimally and precisely as possible):
Update to firewalld 1.0.0-1.1 on openSUSE Tumbleweed. Previous version 0.9.3-3.3 works fine.

Anything else we need to know?:
I didn't try to use the iptables backend, as the latest firewalld shows this new comment:

 ...
+# Note: The iptables backend is deprecated. It will be removed in a future
+# release.
 FirewallBackend=nftables
...

Environment:

• Firewalld Version: 1.0.0-1.1
• Firewalld Backend: FirewallBackend=nftables
• OS: openSUSE Tumbleweed snapshot 20210818
• Others: This is on a ROCK64 SBC, aarch64 architecture.

I'd be glad to provide any additional information or logs.