Thanks for your response.
I found out that this is because of the Power Platform CLI versions. The portal configurations in source control was downloaded with a previous version, when I tried to upload them back, I had updated the CLI to a newer version.
Luckily, I could run paportal to download the portal configurations to a different folder, and compare with the ones in source control, and copied over the configurations for polling options. Then I could upload it again.
This is why we need to be careful with preview feature!