MacBook Air keeps restarting because of a problem?

Try running the Apple Diagnostics to see if any issues are detected.

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

If we cannot detect a software issue causing your problem then there is a secret free Apple repair program for some MBAir 2018 Logic Boards. Have Apple or an Apple Authorized Service Provider examine the laptop to see if your laptop qualifies.

FYI, here is the current list of publicly acknowledged free repair programs for various Apple products (some products have multiple programs):

https://support.apple.com/service-programs

There is no fighting Apple on it. When an Apple technician enters your serial number into their online service portal Apple will inform the tech whether you laptop qualifies for the free secret repair program. Either the laptop qualifies or it does not. Personally I think it is worth having them check it out especially if you have one of the laptops which qualifies.

Post the EtreCheck report here using the "Additional Text" icon which looks like a piece of paper. The EtreCheck report is made to be posted here or you must pay to have the developer interpret the report for you. The report won't actually tell you what is bad (except for mentioning possible adware). The regular contributors on these forums understand how to interpret the EtreCheck report.