Most cookies not loading, lag burst upon opening Brave

I’ve been having a problem for a few months now and I finally tried making an account here to try and get help on it: Whenever I boot up Brave recently, there’s this big burst of lag that lasts for a few minutes mid-way through opening my last session up. When it ends, it doesn’t register as me having any cookies for log ins, although some stuff remains, like Dark Mode being enabled on YouTube. I think there might be an error in reading the cookies and interpreting them but I’m not sure how I can fix them. One of the first things I tried was clearing them all away but it didn’t seem to change anything. So… I’m at a loss.