From the FAQ on https://www.thunderbird.net/donate/

We understand that your privacy is very important -- we agree, and that's a core value of ours at Thunderbird and Mozilla. Your address is part of our Payment Processing, Contact and Donation Information that we outline in our Privacy Policy. This data is used for payment processing, transactional receipts, fraud detection and record-keeping purposes. If you want to know more about the personal information data we receive, the third-party vendors we trust, and how long we keep your data, please refer to our Websites, Communications & Cookies Privacy Notice.

If you had offered Visa payment or Paypal I would have donated, but I will not give all this information for some unknown private payment system

If you had offered Visa payment or Paypal I would have donated, but I will not give all this information for some unknown private payment system

Did you read the information? what do you mean by 'unknown payment system' - I've no idea what you are seeing but it's not what I see.

Is my donation secure? Yes, we use industry-standard SSL technology to keep your information secure. We partner with Stripe, the industry's established payment processor trusted by some of the world's largest companies. Your sensitive financial information never touches our servers. We send all data directly to Stripe's PCI-compliant servers through SSL. We understand that your privacy is very important. For complete information please refer to the Mozilla Privacy Policy.

I just looked and it does offer those options: On the donate page below it has FAQ's and this one says

What are the ways I can give? You can donate online securely by credit card or PayPal, Google Pay, Apple Pay, and by bank transfers through SEPA, iDEAL and ACH. Give in your local currency! We accept over 100! Choose yours from the drop down menu next to ‘Amount’. You can give offline in USD only by mailing a cheque or money order made payable to "MZLA Technologies Corp". Mail to:

MZLA PO Box 25718 Pasadena CA 91185-5718

Please include your email address on the memo line of your cheque to help us track and attribute your gift. We can only send acknowledgement receipts by email.

And here it says : https://www.mozilla.org/en-US/privacy/websites/ Payment Processing: When you purchase something via a Mozilla website, contribute funds or make donations, you will send payment through one of our third-party payment providers: Stripe, Apple Pay, PayPal, Venmo or Google Pay. Mozilla receives a record of your account (including your billing address and the last four digits of your payment method) and (where relevant) the status of your account’s subscription; we may also receive your name, mailing address, and/or email address. This data is used for payment processing, fraud detection and record-keeping purposes.

Contact and Donation Information: We use Acoustic, Salesforce, Fundraise Up and Campaign Monitor to email receipts and store records, which are retained for 10 years from the date of last payment. If you make a donation to the Mozilla Foundation or Thunderbird, we use Fundraise Up to manage our donations and provide transactional receipts to donors.

If I need to make a payment to anyone via online using a card, the bank will demand certain information such as the name on the card etc. It's all to do with fraud prevention.

Also located this:

How do I get a receipt? You will receive an email confirmation whenever you donate and this will include a receipt for your records. You can also access your receipt history at any time from our Donor Portal.

So obviously they would need to know who to send it to and in order to offer you access to Donor Portal which is important from a donor point of view they need to create an account using info supplied.

If I go to 'https://www.thunderbird.net/en-US/donate/ I can only choose Donate and Support where full name, mail address, home address: street ... is required. This information is handled by Mozilla the unknown private payment system) I see no direct link to Paypal or bank transfer. I assume that Mozilla sends this to Paypal, bank, etc. but Mozilla also has access to the information. I need a direct link to Paypal or Bank transfer or an account number