Made a ticket before, admin closed while probably not reading and seeing that the issue was not related to the fact that I used 1.12.2. This is on the stable 1.16.5 server.
>java -Xmx1G -Xms1G -jar forge-1.16.5-36.1.0.jar
2021-06-21 18:28:28,771 main WARN Advanced terminal features are not available in this environment
[18:28:28] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmlserver, --fml.forgeVersion, 36.1.0, --fml.mcpVersion, 20210115.111550, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge]