Invalid Pointer errors when launching certain games

Your system information

• Steam client version (build number or date):
  

• Distribution (e.g. Ubuntu): Arch

• Opted into Steam client beta?: Yes

• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

https://gist.github.com/DGauze/c4ceeffe9619f4cdb7bcc661bddf1a7f

When I try to click play, the game acts as if it's open but nothing comes up at all. The play button on steam has turned into the big blue stop button, implying that something is happening but it never does.

The error codes I've been getting are either:

• "munmap chunk(): invalid pointer" (Yes, with NO error code to follow it up. It's just a blank invalid pointer error),
• "free (): invalid pointer"
• "double free or corruption (out)" (As shown in the above gist)

So I've been having this issue as of late with 3 games in particular: Battlefield 4, Kenshi, and Warframe. These games have launchers of some sort.

I have timeshifted all the way back to a 3 month old snapshot and all of these games worked flawlessly. After updating off of that snapshot again, Battlefield 4 continues to work but the other two simply don't. I'm at a loss as to what to do, and any googling of this error online has left me empty handed as I tried ALL of their solutions to no success.

Steps for reproducing this issue:

1. Launch Steam
2. Go to Warframe
3. Click Play.

Start with the linked gist and the reproduction steps for Warframe on Arch using the Steam client beta. Compare the failing launches with the older Timeshift snapshot and the Battlefield 4 case, then determine whether the invalid-pointer errors can be reproduced consistently. Done means identifying a confirmed Proton or environment cause and documenting a verified resolution.