There are two current issues with the telegraf prometheus-client listen-address configuration. It seems to accept multiple address values, However it seems to only be able to accept one address in the configuration file, It also does not provide brackets around IPv6 addresses causing a too many colon error when using a single IPv6 Address.
Sep 8 17:21:04 vyos telegraf: 2022-09-08T17:21:04Z E! [agent] Failed to connect to [outputs.prometheus_client], retrying in 15s, error was 'listen tcp: lookup '172.16.4.155', '2602:fb68:3::155': no such host'
Sep 8 17:25:10 vyos telegraf: 2022-09-08T17:25:10Z E! [telegraf] Error running agent: connecting output outputs.prometheus_client: Error connecting to output "outputs.prometheus_client": listen tcp: address 2602:fb68:3::155:9273: too many colons in address