Port net-mgmt/telegraf does not build anymore since last version 1.19.3

Version 1.19.2 net-mgmt/telegraf builds just fine on my system with
FreeBSD 12.2-RELEASE-p10 (amd64).

But version 1.19.3 gives the following error:

...

===>>> Waiting on fetch & checksum for net-mgmt/telegraf <<<===
# get https://proxy.golang.org/sigs.k8s.io/apiserver-network-proxy/konnectivity-client/@v/v0.0.14.zip
# get https://proxy.golang.org/sigs.k8s.io/apiserver-network-proxy/konnectivity-client/@v/v0.0.14.zip: 200 OK (0.113s)
# get https://proxy.golang.org/sigs.k8s.io/structured-merge-diff/v3/@v/v3.0.0.zip
# get https://proxy.golang.org/sigs.k8s.io/structured-merge-diff/v3/@v/v3.0.0.zip: 200 OK (0.112s)
# get https://proxy.golang.org/sigs.k8s.io/structured-merge-diff/v4/@v/v4.1.0.zip
# get https://proxy.golang.org/sigs.k8s.io/structured-merge-diff/v4/@v/v4.1.0.zip: 200 OK (0.124s)
# get https://proxy.golang.org/sigs.k8s.io/yaml/@v/v1.2.0.zip
# get https://proxy.golang.org/sigs.k8s.io/yaml/@v/v1.2.0.zip: 200 OK (0.112s)
# get https://proxy.golang.org/sourcegraph.com/sourcegraph/appdash/@v/v0.0.0-20190731080439-ebfcffb1b5c0.zip
# get https://proxy.golang.org/sourcegraph.com/sourcegraph/appdash/@v/v0.0.0-20190731080439-ebfcffb1b5c0.zip: 200 OK (0.113s)


===>  License MIT accepted by the user
===>   telegraf-1.19.3 depends on file: /usr/local/sbin/pkg - found
===>   telegraf-1.19.3 depends on file: /usr/local/bin/go - found
===>   telegraf-1.19.3 depends on package: ca_root_nss>0 - found
===> Fetching all distfiles required by telegraf-1.19.3 for building
===> Fetching github.com/influxdata/telegraf dependencies
===>  Extracting for telegraf-1.19.3
=> SHA256 Checksum OK for go/net-mgmt_telegraf/telegraf-v1.19.3/v1.19.3.mod.
=> SHA256 Checksum OK for go/net-mgmt_telegraf/telegraf-v1.19.3/v1.19.3.zip.
go: finding module for package github.com/Azure/go-amqp
github.com/influxdata/telegraf/plugins/inputs/eventhub_consumer imports
        github.com/Azure/azure-event-hubs-go/v3 imports
        github.com/Azure/go-amqp: cannot find module providing package github.com/Azure/go-amqp: module lookup disabled by GOPROXY=off
*** Error code 1

Stop.
make: stopped in /usr/ports/net-mgmt/telegraf

===>>> make build failed for net-mgmt/telegraf
===>>> Aborting update

===>>> Update for net-mgmt/telegraf failed
===>>> Aborting update


===>>> You can restart from the point of failure with this command line:
       portmaster <flags> net-mgmt/telegraf 

This command has been saved to ~/portmasterfail.txt

The message suggests on issue with my GOPROXY settings. I have not
changed any GO settings, e.g. I am using defaults only:

# env |grep -i proxy
The above command yields no output.

# go env |grep -i proxy
GONOPROXY=""
GOPROXY="https://proxy.golang.org,direct"

I have contacted the port maintainer and he suggested to even remove
the GO default setting. I tried:
# go env -w GOPROXY=no
according to https://golang.org/ref/mod#goproxy-protocol but the issue
remains.

I appreciate any hints into the right direction.

Peter