1. Start the operation in a browser, inspect it, copy as cURL, cancel it.
2. Login to VPS, paste cURL appending `-o <filename>`.
3. When finished, `tailscale file cp <filename> <machine>:`.
A bit of a faff, but 100% reliable.
Might not be faster, but I don't care. It always completes without me having to retry it.
I run Tailscale on all my devices, all the time. This particular VPS isn't exposed on any public ports. This is better for everything, and saves me – not a Linux sysadmin by trade – a ton of time.
As a result, I get the very convenient and fast `tailscale file cp` command for free. You're telling me that the minuscule number of extra cycles it takes over `scp` is a "waste of resources"? Have a look at yourself.