Test utilizing http_proxy env var is failing on eap 81. It is working fine on wildfly and eap 80 variants.

I assume it should work that https://github.com/jboss-container-images/openjdk/blob/ubi9/modules/proxy/artifacts/opt/jboss/container/java/proxy/proxy-options#L39 provide http.proxyHost and http.proxyPort system properties to EAP. 
That is what I really see in when running with EAP 8.0 image

http.proxyHost = mitm
http.proxyPort = 3128

Those are missing when running with EAP 8.1 images. So I assume there is some change in parsing http_proxy value

There is difference in java used in images

81 image (not working) : java.vendor.version = (Red_Hat-17.0.13.0.11-1) 
wildfly image (working): java.vendor.version = (Red_Hat-17.0.12.0.7-1)
80 image (working): java.vendor.version = (Red_Hat-17.0.12.0.7-1)