Subject is a crown on a branch. Just after the video start blind rain started. Sun was back-lighting crown, rain and autumn foliage. Sony RX10 III enables continues focusing in slow motion and there is no possibility to switch it off. Looks like rain drops in foreground misled auto-focusing system and crown went out of focus. As a suggestion in such cases, after the slow motion is switched ON and focus locked, switch focusing to manual mode. That shall prevent cameras from refocusing.
1000fps gives a significant quality drop on a Sony RX10 mk3.
Next time I will try to use 500fps or 250fps.