shellcheck --version or "online"): #!/your/interpreter
your script here

Same thing happening to me since early today.
Running scoop virustotal shellcheck results in 1/64 (Microsoft, Trojan:Win32/Fuery.C!cl).
See also: https://www.virustotal.com/#/file/1763f8f4a639d39e341798c7787d360ed79c3d68a1cdbad0549c9c0767a75e98/detection
However, IMHO, this looks as a false-positive.
I received the same message today when I ran my Windows system

It says its a trojan horse and it's dangerous, as you can see I installed spellcheck using chocolatey
This has happened on my system also, with Shellcheck 0.7.1 on Windows 10 1909.
New scan https://www.virustotal.com/gui/url/2355c0cfbbc9e0aa842eeee596c658382387c3c3b3dae2f922a47c69ef80ff91/detection
and Microsoft does not longer report the Trojan for the https://github.com/koalaman/shellcheck/releases/download/v0.7.1/shellcheck-v0.7.1.zip
Here is another scan which is green too https://metadefender.opswat.com/results#!/url/aHR0cHM6Ly9naXRodWIuY29tL2tvYWxhbWFuL3NoZWxsY2hlY2svcmVsZWFzZXMvZG93bmxvYWQvdjAuNy4xL3NoZWxsY2hlY2stdjAuNy4xLnppcA==/overview
However, the file downloaded locally is reported as infected for me too
Same here: