The deposit could be from a platform or service that works with Stripe for payments. Platforms like SquareSpace, Shopify or crowdfunding platforms like Kickstarter accept payments and get paid using Stripe.
Check your other Stripe accounts if you have multiple
Review the payouts in your dashboard. If you are on an automatic payout schedule, you can review the Transactions section to help you reconcile what's included in your payout
If you are unable to verify the source of the money deposited into your bank account, or if you need help getting in touch with a platform that you might have used to accept payments, contact Stripe support.