The condition is checking if the previous "Get items" returns 0 (the specific user didn't have an list item in the list) or 1 (the specific user does have an list item in the list), and the expression is:
"expression": {
"and": [
{
"equals": [
"@length(body('Get_items')?['value'])",
1
]
}
]
},
> Once I know what the condition is checking for, then I will probably understand why you are either updating
> or creating an item in SharePoint. However, what is the relationship of the SharePoint list to a Microsoft
> Forms submission? They're two different things.
Team members should submit the form (Microsoft Forms) daily and the SharePoint list should be updated daily according to the form submissions (their first submissions should create list items).
FYI. When I had the following result (before the test, there was only one item is the list. The existing one was updated, but another list item was also created/added. I mean the second item should NOT be created/added):

The output of the "Update item" was as follows:
{
"@odata.etag": "\"3\"",
"ItemInternalId": "43",
"ID": 43,
"Title": "Full day available",
"TeamMember": {
"@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
"Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"DisplayName": "Kaz Suzuki",
"Email": "ksuzuki@companydomain.com",
"Picture": "https://companydomain.sharepoint.com/sites/SolutionsInnovation100-Test-Availability/_layouts/15/UserPhoto.aspx?Size=L&AccountName=ksuzuki@companydomain.com"
},
"TeamMember#Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"Availabilityin_x0025_": 8,
"Updated": "2025-01-27",
"UserID": "ksuzuki@companydomain.com",
"Modified": "2025-01-27T14:46:29Z",
"Created": "2025-01-27T14:30:20Z",
"Author": {
"@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
"Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"DisplayName": "Kaz Suzuki",
"Email": "ksuzuki@companydomain.com",
"Picture": "https://companydomain.sharepoint.com/sites/SolutionsInnovation100-Test-Availability/_layouts/15/UserPhoto.aspx?Size=L&AccountName=ksuzuki@companydomain.com",
"Department": null,
"JobTitle": null
},
"Author#Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"Editor": {
"@odata.type": "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
"Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"DisplayName": "Kaz Suzuki",
"Email": "ksuzuki@companydomain.com",
"Picture": "https://companydomain.sharepoint.com/sites/SolutionsInnovation100-Test-Availability/_layouts/15/UserPhoto.aspx?Size=L&AccountName=ksuzuki@companydomain.com",
"Department": null,
"JobTitle": null
},
"Editor#Claims": "i:0#.f|membership|ksuzuki@companydomain.com",
"{Identifier}": "Lists%252fMembers%2bGeneral%2bAvailabilities%252f43_.000",
"{IsFolder}": false,
"{Thumbnail}": {
"Large": null,
"Medium": null,
"Small": null
},
"{Link}": "https://companydomain.sharepoint.com/sites/SolutionsInnovation100-Test-Availability/_layouts/15/listform.aspx?PageType=4&ListId=099d88e2%2D5202%2D4aee%2Db7d1%2D1f9d8a1ebab9&ID=43&ContentTypeID=0x0100F5A47305E7E3A54B821597EC14791820005EC0943254B51B408C37BEC026F62581",
"{Name}": "Full day available",
"{FilenameWithExtension}": "Full day available",
"{Path}": "Lists/Members General Availabilities/",
"{FullPath}": "Lists/Members General Availabilities/43_.000",
"{HasAttachments}": false,
"{VersionNumber}": "3.0"
}