I suspect this might be happening due to Gesture recognition - if this feature is enabled a raised palm in the Zoom video will trigger the Raised hand reaction.
To check if the feature is enabled please go to your Zoom client
- Click your profile picture, then click Settings.
- Click General

- Under Reactions, uncheck the check box to disable Activate the following emojis based on hand gesture recognition: 👍 ✋
Please see the article below for more information:
https://support.zoom.us/hc/en-us/articles/4407537406093-Using-gesture-recognition