Use the 32-bit RPi OS. That fixed it for me.

EDIT:
Nevermind. It's still crashing. Terminal output is the same when I was using the 64-bit RPi OS. Would even close everything and return to the login screen sometimes...very weird. Was able to play games for a few hours though, shutdown, boot, then segfaults.

EDIT 2:
Apparently, the only difference I made was toggle Big Picture Windowed mode to On. Too bad this is the only way for my host PC to change its screen resolution (Ultrawide - 2560x1080) to match my TV (4k -> 1080p). Turning it Off makes the SegFaults go away.

Can you post a link to the Steam logs\streaming_log.txt from your host PC?

Originally posted by slouken:

Can you post a link to the Steam logs\streaming_log.txt from your host PC?

Exact same issue, so here's the logs:

[2026-08-05 22:38:01] Client version: 1785799196
[2026-08-05 22:38:01][4.719955] Desktop state changed: desktop: { pos: 0, 0 size: 1920,1080 } primary: { pos: 0, 0 size: 1920,1080 }
[2026-08-05 22:38:01][4.720476] Caching cursor image for , size 32x32, serial 94, cache size = 0
[2026-08-05 22:40:35][159.421359] Clearing capture only gameID
[2026-08-05 22:40:35][159.422217] Streaming initialized and listening on port 27031
[2026-08-05 22:40:35][159.424553] Caching cursor image for , size 32x32, serial 3, cache size = 1
[2026-08-05 22:40:35][159.427649] GameScope focus changed to appID 0
[2026-08-05 22:40:35][159.479006] Caching cursor image for default, size 32x32, serial 92, cache size = 2
[2026-08-05 22:40:35][159.479071] GameScope focus changed to appID 0
[2026-08-05 22:40:35][159.594211] Window title set to Steam
[2026-08-05 22:40:35][159.628167] Caching cursor image for , size 32x32, serial 93, cache size = 3
[2026-08-05 22:40:35][159.628262] GameScope focus changed to appID 0
[2026-08-05 22:40:35][159.628345] Window title set to
[2026-08-05 22:40:42][166.347607] Caching cursor image for , size 32x32, serial 95, cache size = 4
[2026-08-05 22:41:10][193.943551] Caching cursor image for , size 1x1, serial 99, cache size = 5
[2026-08-05 22:41:20][204.623059] GameScope focus changed to appID 0
[2026-08-05 22:41:21][204.935504] GameScope focus changed to appID 0
[2026-08-05 22:41:25][208.739156] GameScope focus changed to appID 0

What I did:
1) Launch Steam on my PC
2) Launch Steam Link on my Raspberry Pi
3) Try to connect to my PC via Steam Link (it segfaults)
4) Come back to my PC to find it is in Big Picture Mode when it wasn't before. Exit Big Picture Mode
Forgot to add that I did not try what worked for OP. This is with Steam Link in fullscreen.

@slouken
I know why it happened! I knew it was familiar. Oh boy is this a doozy.
Okay, so as of the release of the Raspberry Pi 5, Raspberry Pi OS now ships with 16k pagefile sizes instead of 4k. A lot of faster ARM devices need 16k because of their underlying architecture, and since 16k kernels work just fine on 4k hardware, 16k is now the default on Raspberry Pi OS. Ditto with Asahi Linux, if you have ever heard of it.
Now, if you have an app that is compiled for 16k, it can run just fine on a 4k kernel, but a 4k app will segfault on a 16k kernel. So how do you fix it? Fortunately, other apps have had to solve this same problem. Chromium already solved it,[issues.chromium.org] but that is just one example that I pulled from Asahi's very helpful documentation[asahilinux.org] that addresses this topic.
While the team is at it, I also opened this:
https://steamcommunity.com/groups/SteamClientBeta/discussions/3/657107714318538189/
If you wouldn't mind suggesting to the team the idea of building the upcoming Steam Client for ARM Linux with 16k pagefile sizes as well, I would much appreciate it.

Originally posted by EclecticEman:

@slouken
I know why it happened! I knew it was familiar. Oh boy is this a doozy.
Okay, so as of the release of the Raspberry Pi 5, Raspberry Pi OS now ships with 16k pagefile sizes instead of 4k. A lot of faster ARM devices need 16k because of their underlying architecture, and since 16k kernels work just fine on 4k hardware, 16k is now the default on Raspberry Pi OS. Ditto with Asahi Linux, if you have ever heard of it.
Now, if you have an app that is compiled for 16k, it can run just fine on a 4k kernel, but a 4k app will segfault on a 16k kernel.

Steam Link uses the system allocator, so page size shouldn't matter in this case. Just to be sure, can you confirm that running a kernel with 4k page sizes fixes the issue?

Short answer is that it does not work on 4k.
Long answer is that, even though everything I read online said they had switched to 16k, for some reason when I went to test it today I checked and found I was running the 4k kernel. I guess Raspberry Pi still installs both (I was able to confirm that much), and supposedly it fires up the 16k kernel by default, but either way I was booted into the 4k kernel and Steam Link still segfaulted in the exact same manner.