Powershell 7 fails when uploading a file with Invoke-RestMethod for multipart form but works in Powershell 5

I am uploading files to a resource using REST in the following way.

    #File names    $PathToFile = "C:\Path to file here.zip"    $PackageName = $(Split-Path $PathToFile -Leaf)    #Byte stream and encoding    $PackageByteStream = [System.IO.File]::ReadAllBytes("$PathToFile")    $Encoding = [System.Text.Encoding]::GetEncoding("ISO-8859-1")    $FileEncoding = $Encoding.GetString($PackageByteStream)    #Create the content body    $Boundary = (New-Guid).ToString()    $ContentBody = "--$BoundaryContent-Disposition: form-data; name=""files""; filename=""$PackageName""Content-Type: application/octet-stream$FileEncoding--$Boundary--"    #Parameter Object    $Parameters = @{        Uri                   = "http://myUrlhere.com/TargetResource"        Method                = "Post"        UseDefaultCredentials = $true        ContentType           = "multipart/form-data; boundary=`"$Boundary`""        Body                  = $ContentBody    }    if ($IsCoreCLR -and ($Parameters.Uri -match '^http:')) {        $Parameters += @{ "AllowUnencryptedAuthentication" = $true }    }    #Upload the file    Invoke-RestMethod @Parameters

This works in Powershell 5.1 but in Powershell 7 it fails with "Offset to Central Directory cannot be held in an Int64". The only related post I could find on that was someone who used ReadAllText instead of ReadAllBytes, but since I already use ReadAllBytes I don't think it's that.

Is there something that has changed between Powershell versions that would cause this behaviour?