Many banks use MFA (or Multiple Factor Authentication) for secure login purposes. When you first imported your bank data into LessAccounting, you might have answered one security question, but now the bank is asking another question that we don't have the answer to yet.
The frequency really varies when it comes to how often banks prompt their customers with new security questions. I've seen some banks prompt their users every few months. There are a few who are more diligent about confirming (and re-confirming) that it's still their customer who wants the data. That means, they prompt you to answer security questions often-- sometimes monthly. We do send out email notifications whenever you need to answer a security question and we also post a notification on your LessAccounting Dashboard under your "Tasks & Notifications", so you should always be aware of when you need to do this.
I understand it's inconvenient, but there's no way for us to get around it. We have to play by your banks rules and in the end it's for the safety of your data.