Some Virtual Machine backup solutions use the SQL Server VSS writer service to make SQL Server database backups as part of the VM backup.
You may not have had visibility on this process so to confirm if this is happening in your environment open up SQL Server Management Studio (SSMS) then in Object Explorer right click on the instance name, click on new query and run the script below.
This query looks for entries in the physical_device_name field of msdb.dbo.backupmediafamily that are not directory paths.
SELECT @@SERVERNAME AS ServerName ,bs.backup_set_id AS BackupSetId ,bs.database_name AS DbName ,bs.backup_start_date AS BackupStartDate ,bs.backup_finish_date AS BackupFinishDate ,CAST(CAST(bs.backup_size / 1000000 AS INT) AS VARCHAR(14)) + ' ' + 'MB' AS [Size] ,bs.[type] AS BackupType ,CASE bs.[type] WHEN 'D' THEN 'Full Backup' WHEN 'I' THEN 'Differential Backup' WHEN 'L' THEN 'TLog Backup' WHEN 'F' THEN 'File or filegroup' WHEN 'G' THEN 'Differential file' WHEN 'P' THEN 'Partial' WHEN 'Q' THEN 'Differential Partial' END AS BackupTypeDescription ,bmf.physical_device_name AS BackupFilePath ,CAST(bs.first_lsn AS VARCHAR(50)) AS FirstLogSeqNo ,CAST(bs.last_lsn AS VARCHAR(50)) AS LastLogSeqNo FROM msdb.dbo.backupset AS bs WITH (NOLOCK) INNER JOIN msdb.dbo.backupmediafamily AS bmf WITH (NOLOCK) ON bs.media_set_id = bmf.media_set_id WHERE bs.[type] = 'D' AND bmf.physical_device_name NOT LIKE '%\%' ORDER BY bs.database_name ASC ,bs.backup_set_id ASC;
For the field BackupFilePath if you see GUID looking entries like {AQ8F5957-2804-4X05-9EE5-109EB87EBCAB}5 the VM backup is probably running full database backups on the SQL Server.
It might be time to review your recovery strategy as the VM backups could be covering the same ground as the SQL Server backups creating a lot of expensive redundancy due to unnecessary replication of work.