since 2026.9.1, getting webrtc error on picture elements card

### The problem

ever since updating to 2026.9.1, my camera feeds from my Eufy cameras will either play for a short while or not play at all...and instead report the following

failed to start WebRTC stream: Stream source is not supported by go2rtc

The video streams themselves play fine in the GO2RTC web UI...first time every time and never stop working

Nothing has been changed in camera output settings in years.....

A prior identical issue (165295) reported back in 2026.3.1 was resolved in 2026.3.2, so it is probably just a bug I should report but might just go away on its own in the next release

I can confirm that going back to 2026.9.0 and 2026.8.3 has fixed the issue for me (although that obviously brings other unrelated version issues)...but the reported issue is no longer there

Clutching at straws a little, but would change 181012 have impacted this... can't see anything else relevant that might have impacted in 2026.9.1

### What version of Home Assistant Core has the issue?

core-2026.9.1

### What was the last working version of Home Assistant Core?

core 2026.9.0

### What type of installation are you running?

Home Assistant OS

### Integration causing the issue

picture entity card

### Link to integration documentation on our website

_No response_

### Diagnostics information

_No response_

### Example YAML snippet

```yaml

```

### Anything in the logs that might be useful for us?

```txt

```

### Additional information

_No response_

Start by reproducing the Eufy camera failure in the picture elements card on core-2026.9.1, then compare its WebRTC/go2rtc behavior with core-2026.9.0 and 2026.8.3. Investigate the regression associated with the picture elements card and change 181012; done means the camera stream starts and remains playable without the unsupported-source error.

Written by the indexing model from the issue text.