Borderlands 2 proton is not installable

**Game information**
Borderlands 2, Proton

**Distribution name and version where applicable**
LSB_VERSION=1.4
DISTRIB_ID=Arch
DISTRIB_RELEASE=rolling
DISTRIB_DESCRIPTION="Arch Linux"

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**Flatpak info**
Flatpak 1.4.0
default
host

**Problem description**
When you try to install Borderlands with Proton (for windows Crossplay) you always end here
after that message, it does something for a minute and pushes out the same message again. Tried on 4 different computers with every time the same. This directory is not available and there are no additional permissions set for the steam flatpak. It's the stock steam flatpak as of today. I'm waiting to finish this for some hours now, tried to reset steam, uninstalled the game and tried with a fresh user. It's always the same message with the same file. Other proton apps work just fine for me.

**Does this issue reproduce with native Steam**
No, only with flatpak steam.