if you're using telegraf to write to monolith, you should be using multiple concurrent writers in nearly every situation. See the docs for the v2 influxdb output plugin: https://github.com/influxdata/telegraf/blob/release-1.36/plugins/outputs/influxdb_v2/README.md
concurrent_writes = 5 # should definitely be at least 2; for tuning, i'd start at min(number of cores for 3ent / 2, 10)
Note: the v1 output plugin for telegraf likely works with v3 but please use the v2 plugin instead.