Dear Astrid,
Good day! Thank you for posting your query in our community.
Based on your description, you can't import a CSV file to create a list successfully. Generally, we create a list based on the CSV file via the "From CSV" option when you create a new list, you can check the following image. And from the screenshot you provided, may I confirm whether you add the "Import CSV Data" button additionally in SharePoint Online?
However, when I tested the above "From CSV" option on my side, I will be stuck on the blank page of the file upload. And I also tested on the different tenants and different devices, the same results.
Given this situation, we assume the problem may be related to the SharePoint backend. And about this behavior, we haven't received any report about it so far. Since we can reproduce a similar situation as yours. We suggest you contact the administrator in your company if you aren’t the administrator and follow the steps in the article to open a ticket to double confirm this behavior. The engineers in the related team have higher permission and resources than us to help check the root cause from the background.
Appreciate your understanding.
Sincerely,
Jazlyn | Microsoft Community Moderator