I'm not sure how quota is calculated with different Basic accounts

I'm a person (not a business) with several Dropbox accounts, linked to different Gmail addresses, for different purposes. I've had Dropbox Plus for one specific project. But it's a big expense for me. Last week, with my renewal date approaching, I wanted to see how much storage I was actually using.

It was a challenge to access my own account details, payment history, and upfront price info — an unnecessarily complex process that felt a bit deliberate. But I finally saw this:

PERSONAL DROPBOX SPACE
USING 4.1GB OF 2 TB

That is, I'm using only 4.1% of what I was paying to have Plus. Even adding more files in the future, I couldn't use 2TB in a million years. That's unwise for me. So I cancelled my upcoming Plus renewal (that is, I downgraded that account).

When I got a warning today, I double-checked. Now, I'm suddenly OVER capacity — because Basic's measured in GB, not TB. Now, I have to buy 1,000x MORE storage than I actually need, because Dropbox offers no middle ground. And the website says:

"(If you exceed capacity) we'll begin by deleting your most recent files to bring your account within the limit, working backward."

Which, obviously, I want to avoid.
This feels a bit bait-and-switchy.

Here's the thing, though: I DO have those other, Basic Dropbox accounts — some with files, some empty. I can divide these files into my other accounts. But I'm hesitant. Could Dropbox combine all my files from all my accounts, then say I'm even MORE over capacity? (I mean, if everyone can have multiple free Dropbox accounts just by using different Gmail addresses, then nobody would have to pay for Dropbox at all. And THAT would be unwise for Dropbox.

Thanks for any clarification.