MacBook Air (2020) slow, overheating, disk space issue

"MacBook Air (2020) slow, overheating, disk space issue: [...]I ran it and it said my only major problem was low hard disk space but when I look in my storage it says I have 82 GB out of 121 GB available. am I looking in the wrong place? does this mean it is probably a hardware issue?"

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Troubleshooting Lagging Mac:

A. Clear System Data:

See how Much fo this is System Data:

System Data is caches, which are created so that app open for efficiently, and open faster, from remembrance of application usage. Use my User Tip: How to Use Finder to Clear “System Data" on a Mac - User Tip

B. See if your Hard Drive is Failing:

Perform the following in Recovery Mode:

1. Boot: into Recovery Mode. Go Here:  How to Use Safe Mode on your Mac- Apple Support
2. Select: Disk Utility
3. Select: the Drive
4. Click: First Aid button

C. Remove Login Items:

While in Safe Mode, remove all of your Login Items, and then restart the Mac.  Go Here: Change Users & Groups Login Items Preferences on Mac - Apple Support

D. Boot in Safe Mode:

In Safe Mode, Login Items do not run at login, certain preferences are set aside, and damaged system files are then reset. So, once booted in to Safe Mode, wait 30 seconds, and then boot up normally, attempting another update install. For instructions, go here: How to Use safe Mode on your Mac - Apple Support

E. Try a New Admin User:

What happens when you create a new administrator user, and log into it? Do you still get this lag? If not, then it is likely an error with the current user. If so, then it is likely an error with your Mac.

"MacBook Air (2020) slow, overheating, disk space issue: [...]I ran it and it said my only major problem was low hard disk space but when I look in my storage it says I have 82 GB out of 121 GB available. am I looking in the wrong place? does this mean it is probably a hardware issue?"

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If my previous reply does not help...

Reinstall the macOS:

Go Here: How to Reinstall macOS from macOS Recovery - Apple Support. Important: Be certain to create a backup of your Mac prior to all of this. That way, you can have something to restore from the Mac from, should anything go wrong with the reinstall. Once reinstalled, try this once more.

How about posting the EtreCheck report here so we can examine it for possible clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

Another vote to post the report. What seems insignificant to a new Etrecheck user can speak volumes to those of us who have reviewed thousands of those reports