Just a suggestion: if you are using the Gmail folders other than input, sent, draft and trash (e.g., allmail, important, etc.). Those are duplicates and you might consider unsubscribing.

Do you mean Gmail and Thunderbird are duplicates, to the Google account? or are they separate from one another? Which do you suggest unsubscribing to? I do have 2 gmail accounts in Thunderbird. One is personal and one is everything else. The personal one account i discovered has large files of photos that i think put me at the 92% storage level. Thank you for your help and any suggestions!

In Thunderbird or indeed any email client - an imap gmail account synchronises with server and displays a copy of what is on the server. Even if you download full copies, you cannot consider an imap account to be a separate independent copy. If you access gmail webmail via a browser or use a phone and delete emails then you will find as soon as you open Thunderbird and it sychronises with server , all those emails will also auto get deleted from the imap account because they do not exist on server. Downloading full copies is useful because it means you can create a backup of your Thunderbird profile. But because imap folders can only show what is on server, it means it's not truelly an independent copy. Lose emails off server and you've lost them in Thunderbird imap account. If your Anti-Virus messes about with any imap mbox email storage file and clears it of emails, then it may end up wiping a load of emails off server. To all intents and purposes the server and an imap account are one and the same.

gmail stores all of your emails (incoming, outgoing, archived) in one folder called 'All Mail'. But gmail knows this is useless and unworkable, so it creates a method of displaying emails in a virtual folder style method. It applies 'labels' which act like a virtual display method. If email in 'All Mail' has a label called 'Inbox' then you see email in the 'Inbox'. The benefit of this means you can display same email in any number of folders.

So, in Thunderbird, if you can see an imap folder called 'All Mail' then you are just duplicating everything. You do not need to subscribe to see the 'All Mail' folder.

The Gmail quota is set by gmail not Thunderbird. It means how much space you are using on the server for storage of emails and images etc.

When you delete emails in an imap gmail account, you must have it set up to put the deleted emails into the imap gmail default Trash folder. Then gmail will auto clear any emails that have been in the TRash for 30 days. Gmail will then remove the email from the 'All Mail' folder so it really has been deleted.

Please make sure you compact folders to remove all traces of previously deleted or moved emails. Right click on folder and select 'compact'.

If you have a load of photos attached to emails, then sort through them. Save any that you really want - store them in a suitable folder somewhere on your computer - not in Thunderbird. Then you can delete the attachment or even delete the whole email.

Gmail quota: https://support.google.com/mail/answer/9312312