Intel(R) UHD Graphics 620 decode related release notes request

[maxcodez]

Intel(R) UHD Graphics 620 decode related release notes request

I am investigating a VP9 decode issue for Chrome:

• Intel(R) UHD Graphics 620
• / Enum\PCI\VEN_8086&DEV_3EA0&SUBSYS_8549103C&REV_02
• i7-8665U CPU
• WinVer 10.0.18363 - 19H2 - 1909

My customer has a base image with DCH 25.20.100.6374.   

It is not immediately possible to experiment with different driver versions. For that reason and approvals required I wish to review documentation first. I want to understand if any similar video decode issue was resolved at driver level since DCH 25.x release.

Questions:

1. Is there a cumulative release notes package available for DCH from 25 through 30?
2. Does 25.20.100.6374 officially support 19H2? - or was 19H2 first supported in a later revision? 
3. DCH 25.x.x branch is no longer available from the usual DCH download location. Is there a reason this branch is no longer available? 
4. Any other info on potential decode issue appreciated.