Hi Booedreaux
Whilst all of these issues are important I wouldn't have thought they would cause such a drop.
One by one:
1. Canonicals - each page should have a self-referential canonical - this stops utm versions created by apps such as Twitter being indexed. It's always better to have them. It also allows you to combine identical pages. Note if you have canonicals in place and the two pages are not the same then Google has recently started ignoring them and listing both URLs anyway so check in new Search Console what Google sees as the canonical.
2. Missing H1 - This helps Google understand the page content and should be a close variant or synonym of the primary keyword.
3. Long URLs - some just are and Google has a pretty high tolerance for long URLs - this often can't be helped with attributes being common on eComm sites.
For more, I'd need to see the URL.
Regards Nigel
