Multiple Issues with MacBook Air (Intel Chip)

To look for possible hardware issues run the Apple Diagnostics.

To look for possible software issues run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper.

Run Disk Utility First Aid on the hidden Container. You may need to click "View" within Disk Utility and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Even if First Aid shows everything as "Ok" click "Show Details" and manually scroll back through the report to see if there are any unfixed errors listed. If there are any unfixed errors listed, then try running First Aid from Recovery Mode/Internet Recovery Mode to see if they can be repaired. If the errors cannot be repaired, then you will need to erase the whole physical SSD before restoring from a backup or clone.

It appears the SSD has indeed failed. If you haven't done so already make sure to backup your important files as this SSD may not work for much longer.

You can either have Apple replace the SSD for you or you can get a third party drop-in replacement from OWC (the OWC SSD will be larger & faster). The OWC SSD will only allow you to run macOS 10.13+ though.

https://eshop.macsales.com/shop/ssd/owc/macbook-air/2013-2014-2015

Run DriveDx so we can check the health of the SSD to see if there is an actual problem with the drive. Please post the complete DriveDx & EtreCheck reports here using the "Additional Text" icon which looks like a piece of paper. In order to properly understand snippet of the EtreCheck you mentioned we need to see the complete versions of both of these reports. It sounds like there may be an issue with the SSD, but sometimes it may be possible to fix an SSD issue, but I need the information from the SSD's health report to make that determination.