Running Tahoe 26.3 is part of this - OBS 32 hasn't been fully tested on the beta yet and there've been some stability reports. But even without that, M1 Air with 8GB + no active cooling tends to thermal throttle around the 45-50 min mark during sustained encoding. Open Activity Monitor while streaming and watch memory pressure and CPU usage - if it goes red near the freeze point, that's likely your culprit.