Ok a few things that I see:
1. When you select an item RecordGallery1, a variable is getting created that stores your selected record. Whenever you save this record, you want to update this variable so you get the most current results in the variable. The best place to do this would be in the OnSuccess property of you form and the formula to update would look like something like this:
UpdateContext({CurrentItem: Self.LastSubmit})
It looks like you are using the new Microsoft canvas app template (auto generation of an app), so this is already likely there.
2. In your custom button, I don't think your need to perform another SubmitForm(Form1) action, as you are already submitting the ✅ icon in your form and this seems redundant from what I see. I would remove this.

3. Since you are already saving the newest record information in the CurrentItem Variable, you will want to use this variable instead of trying to reference your gallery selected item. So you would re-write your Team Chat formula to something like:
MicrosoftTeams.CreateChat(
//Not sure if DataCarValue1.Selected.Email is in relation to your form, but assuming your have a Column called Email in your SharePoint list, this is what you use. If not it might be something like CurrentItem.PersonField.Email
CurrentItem.Email, {
content: Concatenate(
"A new item has been created with the following details: ", CurrentItem.'Nr.' & CurrentItem.'Country' & CurrentItem.'Customer' & CurrentItem.'Weight' & " is completed."
),
contentType: 0
}
)
I tried testing this, but I was not able to get a teams message sent in my environment (but no error). If you have no luck with this, you might try using power automate, see this thread:
Solved: Powerapp create Microsoft team chat - Power Platform Community
Another option:
Microsoft Teams messages from Power Apps - 365 Corner
Edit:
I did get the Create Chat to work, but I had to use this syntax:
MicrosoftTeams.CreateChat("AdeleV@0v42t.onmicrosoft.com", {topic: $"topic: {CurrentItem.Coat}"})
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Cheers!
Rick Hurt