The image fails to download because the www.serial-kombi.com webserver is misconfigured. It’s sending an incomplete certificate chain. The intermediate certificate is missing.
Most browsers probably have the “Sectigo RSA Organization Validation Secure Server CA” intermediate certificate cached from another site, so it’s not an obvious issue. The download fails, because AFAIK OpenSSL doesn’t have such a cache. It requires the server to send it.
See for yourself in the SSL Server Test for www.serial-kombi.com. It reports an incomplete certificate chain.