TWINT plugin config fails at certificate upload

I installed the TWINT Plugin

When I try to configure the SSL Connection, i can not upload the certificate.

The selected file „12356989-87fe-4ede-9c30-c7cbe85e4a86.p12“ has an unsupported format. Please use one of the following types: application/x-pkcs12.

I checked the validity of the file already via
openssl pkcs12 -info -in 12356989-87fe-4ede-9c30-c7cbe85e4a86.p12 -noout

How can I upload the certificate under
Settings → Extensions → TWINT credintials ?

It looks like a flaky JS
Works on Safari under iOS

Does not Work on Chromium or Firefox under Ubuntu 24.04