I modified a SharePoint list form in PowerApps, I really did nothing other than move some fields around.
And when I test it out, it works then doesn't work, then works, then doesn't work. It is very frustrating. I think this is a serious bug with SharePoint and PowerApps.
The first error is: "There is a problem saving your data. Data source may be invalid"
The second error is: "Conflicts exist on the server, please reload. Server response ETAG mismatch"
Here is a screen shot:
I am not sure if it is related to your issue but there is an open issue on the PowerApps Support page regarding ETAG mismatch.
I saw that before I posted. It was similar but not exact. Just hoping there was something out there for this fix.
I am going to assume there isn't an immediate fix and willl have to live with it for the time being.
This section is much related to CDS being the datasource for PowerApps while your question has a SPO datasource, to enrich discussion i would suggest you post it in the Deneral Discussion or in the Connecting to Data section.
Meanwhile, I am curious about how you have changed the screen recording to gif image..
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