I did this

Set CURLOPT_SSL_CIPHER_LIST on a connection that uses Schannel, TLS 1.2, and make a connection to an HTTPS server.

I expected the following

Investigate its Hello message, the cipher suites should match my settings.

curl/libcurl version

libcurl 7.85.0 to the latest

operating system

Fails (CURLOPT_SSL_CIPHER_LIST has no effect) on Windows 10 build 17763 and above, such as 10 Enterprise 1809 and 20H1.
Works (CURLOPT_SSL_CIPHER_LIST is in effect) on Windows 10 build 14393, such as Windows Server 2016

Cause analysis

The problem was introduced by 8beff43. The change moved this chunk of code:

to However, the new block was an else block started way above Then the logic becomes: Since only Windows 10 build 17763 supports TLS 1.3, we configure only TLS 1.3 ciphers on those systems; if we are on a lower version of Windows, we go ahead and configure TLS 1.2 (or lower) ciphers. So the combination of "on a newer version of Windows 10" and "using TLS 1.2" falls into neither branch. Support for CURLOPT_SSL_CIPHER_LIST under that combined condition was lost.