What are "Uncaptured" payments in Stripe?
When a customer submits your checkout, the first thing that happens is that Subsail attempts to create a payment in Stripe but does not complete the transaction.
The rest of the form is then submitted (an order is placed and a subscription is created in the system) and this is when Subsail completes the payment. Only then is the customer actually charged.
The initial default state of all payments made by Subsail is "Uncaptured". Payments for successful orders will change to "Succeeded".
If you see any "Uncaptured" payments in your Stripe account, you can safely ignore them (or even cancel them if you want to tidy up). They only happen if there is an unforeseen issue at checkout. Your customer will not have been charged.