Re: "2015 MacBook Pro rapidly losing storage after deleting files
2015 Macbook Pro keeps running out of storage space - goes from 19 or so gig down to MBs in a 2-3 hours no matter what I'm doing even if its just surfing, working on a google doc or spreadsheet, writing an email.. It's so bad I haven't been able to update iOS since Catalina 10.15.7."
Apple support provides detailed articles that may help you restore order.
For MacOS Catalina:
You can: See used and available storage space on your Mac - Apple Support
Eg: says:
"Free storage space is physically open space on a disk.
Available storage space includes free storage space and purgeable disk caches (disk space might be both available and used at the same time)."
"To save additional storage space, use the custom storage recommendations for optimising storage on your Mac"
See how to: Optimize storage space on your Mac - Apple Support
Eg: says:
"When space is needed on your Mac, macOS also clears caches and logs that are safe to delete, including temporary database files, interrupted downloads, staged macOS and app updates, Safari website data and more".
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Seems you use iCloud:
You can check out how to: Manage iCloud storage on Mac - Apple Support
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Re: "Sometimes I've dragged some files to my external hard drive, but when I've tried to put them back on my laptop, I get the message my file is corrupted even though, the file was made with the current versions of the different apps and iOS The files are a mess and I don't know how to clean them up expeditiously. I end up losing my place as to where I've gotten up to in the process."
If you can keep an external hard drive using Apple File System (APFS), (or a suitable partition on one) just for Time Machine, you may want to:
Back up your files with Time Machine on Mac - Apple Support
You can keep Time Machine backing up regularly, or just back-up from time to time, or just especially before updating Mac OS. You can generally recover files whenever needed. (Time Machine backs up whatever it hasn't yet backed up, ie: everything since last back-up. Keeps files easily available.)
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Re: "I'd brought the laptop into the apple store where I was told there is nothing wrong with the files themselves and there are malware, viruses, or worms issues".
Unnecessary third-party (non-Apple) virus-checker apps often cause disturbing issues on Macs ... use un-installers from their developers to remove any virus-checkers, ad-blockers, cleaners, and the like, (also VPN if not supplied by an employer). The uninstallers (often supplied in the install package) should remove any stray associated files at the same time.
Any third-party apps you find necessary should be kept compatible with the macOS Catalina. Out-dated apps, browser extensions etc. can cause compatibility issues.
See: Ways to avoid malware and harmful apps on Mac - Apple Support
Also: When space permits you could try downloading and running the free version of Malwarebytes, which is especially developed to run on Macs.
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Useful resource for macOS Catalina: macOS User Guide - Apple Support
