Answering this myself - this was PEBKAC…
It appears the InfluxDB 1.x section in my Telegraf configuration was uncommented somehow - so the error messages were coming from that. However, the InfluxDB 2.x output for Telegraf is functioning correctly.
Answering this myself - this was PEBKAC…
It appears the InfluxDB 1.x section in my Telegraf configuration was uncommented somehow - so the error messages were coming from that. However, the InfluxDB 2.x output for Telegraf is functioning correctly.