GloriousEggroll has released a new custom build of their Proton fork.

Proton-6.10-GE-1

-Added UE4 preinstall workaround for Necrumunda
-Added UE4 preinstall workaround for Deliver us the Moon
-Added fix for Guilty Gear XX Accent Core R 2 hang
-Added Horizon Zero Dawn animations patch
-Added FarCry regression hotfix
-Origin seems to be much more stable/reliable now in regards to installation and launching
-Added staging bcrypt patches rebased on top of proton rdr2 patches (allows Steep online mode to work again)
-Added proton nvapi updates
-Added proton QPC performance patches (should help with fps regression)
-Added proton LFH performance patches (should help with frame times)
-dxvk updated with proton latency fixes
-vkd3d updated with proton latency fixes
-faudio updated
-steamclient updated with splitgate fix

Additional notes:

-As mentioned, Origin seems to have returned to stability. I was able to install Mass Effec:LE, Battlefield V, and Mirror's Edge on first launch without issue, and was able to launch Mirror's Edge multiple times consecutively without Origin failing. You may still need to remake the prefix and clear Steam's download cache once in a while to get it to start the Origin install on new prefix, but it seems it's at least not randomly dying any more.

-Due to latency, QPC, and LFH patches, frametimes in Cyberpunk look way better now.

-This build is recommended over the 6.8/6.9 builds due to a lot of fixes, regression hotfixes, and performance tweaks/patches. There have been reports of performance regressions in 6.5+ but apart from one specifically that the QPC patches now resolve, and the one the childwindow patches resolved, I'm unaware/unable to reproduce any others.

Download Proton 6.10-GE-1 from GitHub
Installation Instructions