Gmail: deleting correspondence for several years with megabyte attachments - total + 200kb of space.?

Question

gmail

Went over the 15GB limit.
Correspondence since 2014, almost every second letter with an attachment of 1-3mb graphics.
I delete correspondence 2014-2020 about 3000 letters with all attachments over 3mb - residual space is 14.73GB.
I delete an individual author all the way up to 2020 (1000 letters, 1mb-3mb each) - the rest of the space is 14.53GB.
Is Google mocking me by trying to make me pay, or sponsored me with rubber hosting for free, now returning the surplus and going to zero?

In thunderbird, the save of the entire gmail is not restored - an error and that's it, without explanation.
Therefore, you will have to somehow struggle with the gmail box, but all the letters are needed, and Google has a minimum of manipulations. In general, tell me why when taking out gigs from mail, free space is added in kilobytes?
ps life hacks studied in all languages, admin rights, after deletion, the trash is cleaned.

Answer 1

not so long ago I deleted my junk from gmail. So it turned out that after cleaning the inbox, you also need to clear the "All Mail" folder (deleted from thunderbird). It is duplicated with inbox. After that, I redirected the gmail mail to the mail in yahoo. These are not such goons and give 1TB for free

Answer 2

At Google, all folders are labels for messages. The messages are in the All Mail folder.
To begin with, I would save all the mail in outlook, for example, so that it was, and then I would delete everything in the browser on gmail.com.
If it is desirable to save this mail for access through other clients, make another mailbox on gmail and in outlook drag the necessary messages from one mailbox to another - yes, for a long time, it will hang and write that it "does not answer", but it does.

Answer 3

Google has confirmation of changing the disk size after deleting emails, etc. - occurs within a day or so.
I recently cleaned up the excess.