Can Unreported Capital Loss from 2018 Carryover to 2021 Tax Return?

Bit of an interesting scenario here: capital loss from 2018 was unreported because I was a dependant and didn't think I had to report (never received notifications from IRS, made an online account, and didn't see any notices there either so I hope I'm safe). Also because I was ignorant about dealing with finances.

 

1. Wondering if I could offset this year's gains using those losses.

2. Should I be concerned about not reporting in 2018 and follow up somehow?

 

Thank you.