Stripe will disconnect your payment gateway in Thinkific if they deem you to be carrying out a prohibited business as this breaks their terms of services. Examples of some services include regulated or illegal products/services, unfair and deceptive practices and others, which can be found here.
If you are uncertain as to whether your business is a prohibited business or have questions about how these requirements apply to you, please contact Stripe.
Once Stripe has flagged your business and notifies you of the breach, you should explore other payment options. This includes using Paypal or using an external checkout.
For customers on Essentials plans and above, you should review your courses pricing payment plans, ensuring that your courses no longer have price subscriptions. Paypal does not currently support a simple way to set up payment subscriptions on Thinkific.
Once you have an alternative payment gateway established, reach out to the Thinkific support team to disconnect your Stripe account.