What can I do to get assigned to another project quickly?

Take the initiative! If you are lacking certain skills to get put on new projects, build up those skills. This can be done with side projects, and Taro has a lot of onramps for the specifics you mentioned as well:

• Data engineering - We have a Book Club going over The Fundamentals Of Data Engineering. Attend future sessions (join #taro-bookclub in the Taro Premium Slack if you haven't already), watch recordings of past sessions (they're linked on the Taro event pages), and connect with people who attend the meetings.
• Machine learning - We have a ton of paper reading groups held by MLEs. Follow the advice I gave about the Book Club above. Here's a great sessions going through arguably the most famous paper about machine learning today (it's by Google): https://www.jointaro.com/event/paper-reading-attention-is-all-you-need/

Since you're unassigned, I imagine you have a lot of free time to do this "extracurricular" learning.

On top of that, I recommend just building up the relationship with your bosses so they'll believe you when you say that you can learn quickly: [Masterclass] How To Build Deep Relationships Quickly In Tech

People in charge assigning projects asked me if I have experience in a specific set of technologies but they are mostly related to data engineering or AI/ML and I'm a backend developer.

I don't have experience with working at a consulting company, but there's a similar underlying job searching theme of "how do I get hired at a company if I don't have the required experience".

I would try to position your experience in a way where you are either 1. a generalist SWE whose experience can transfer to either domain or 2. you are willing to learn about either the data or AI/ML domain during the project.

In the meantime, you find out more about how to get started in data engineerings or AI/ML engineering like @Alex mentioned above.