Chat won't sync between 1.20 and 1.8 servers

[lyra56k]

Describe the bug
Cross-server chat does not work at all between a server on 1.20 and a server on 1.8.

Full startup log of affected servers

N/A

To Reproduce
Steps to reproduce the behavior:

1. Install a new Paper 1.20 and Paper 1.8 server
2. Connect them through BungeeCord
3. install MultiChat on both
4. Enable global chat sync
5. Connect one account to each server, and send chat messages on both.

Expected behavior
The chat messages should sync, as they do between 1.20 servers.

Screenshots
N/A

Platform and Versions (please complete the following information):

• OS: Rocky Linux 9.3
• Java Version: Java 8 for MC 1.8, Java 17 for MC 1.20
• MultiChat Version: 1.9.5
• Proxy Version: Waterfall 1.20-556
• Local Server Version: Paper 1.20.1-69, Paper 1.8.8-445

Additional context
Add any other context about the problem here.
Chat sync works fine between my 1.20 servers, the 1.8 server seems to be the issue.

[lyra56k]

Actually, it seems that since I added the 1.8 server, no global chat sync works.