Assuming it's capital in nature and not business income, I recorded my clients on Schedule 3 section 3 (other shares). There really isn't a great spot to put them on Schedule 3.
At the end of the day, as long as the gain/loss is correct, I wouldn't get carried away with how you classify these.
https://www.canada.ca/en/revenue-agency/programs/about-canada-revenue-agency-cra/compliance/digital-currency/cryptocurrency-guide.html