Time Machine Backups taking too much space?

I would probably do two things:

Let time machine run until it fills up the 1.6 TB and then see how long a windows you have. macOS will clean up the destination - purging old files as needed.
Use tmutil compare or a tool like Backup Loupe to check what is taking the space. Other tools do a lousy job of showing you actual space usage in time machine.
- Why does Time Machine estimate a 109GB backup size, but then need 235 GB?
- Time Machine - List of Files that were backed up

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