I think I might have a solution to this problem..
Microsoft has purchased much of Linux world to meticulously kill Linux, the competition, to make Windows be the only operating system that works in phones and computer on the Web, to meticulously destroy Linux, the Poor peoples computers and phones OS.. It's all bout making lots more money...
I had to dump Linux Mint 20 because I found it too buggy and brutal, with too much Microsoft meddling in it..
I dropped back to Linux Mint 19.3.. It's not buggy.. Maybe you can get a clean ISO from Older Versions...
In a new double encrypted install of LM 19.3 I don't do any of the updates, None what so ever.. I install without the Net-connection, is absolutely crucial.. I boycott All the updates.. Microsoft now owns Canonical.. It seems they've put lots of nasty stuff and glitches in the updates to make people start to hate Linux.. The computer is working fine without any of the updates..
At first boot I run Synaptic to completely uninstall: Firefox, Hexchat, Rsync, Transmission, LibreOffice, and everything Bluetooth.. then reboot, change Sources to a trusted university, add BleachBit, and run it, reboot, and add Opera, and disable updates, and add sound codexcs.. Sometimes I even uninstall the Updater.. Then go to extensions, and add Transparent Panel Extension.. Then get a freebie Protonmail email account...
I never ever use an in OS email system like Thunderbird.. Thunderbird is buggie and bad.. This way I can't ever lose any of my email data from a hack-attack that destroys the OS.. Protonmail is super secure, the best of the best.. Protonmail people are as honest and honorable as it gets...
This procedure might stop your computer memory problem..
I always have my precious data stored in seven external hard drives.. This way I can't ever lose my data.. One external hard drive is stored at a relatives, in his fireproof/waterproof floor safe in another city... Do so get an external hard drive as CD's and Flash Drives are not reliable as long term backups... I prefer Toshiba external hard drives.. They last..
Never ever bump an external hard drive while its in operation.. It's best to tape them to the desk.. Never ever run an external hard drive while the machine is connected to the Net... Make your backups today.. Be safe not sorry and sad...