Invidious is more private than using YouTube directly or even most other 3rd party services, but it may not completely prevent Google from tracking you depending on it's hosting, configuration, and usage.

• Are you running the Invidious instance yourself?
  • If so, are you running it on a VPN?
• Are you the only user on this Invidious instance?
• Is Invidious proxying all activity?
• Is the Invidious instance outdated, customized, or noticeably different from most other instances?
• Do you click on links from comments or video descriptions?
• Do you first obtain YouTube links or video IDs and then convert them to an Invidious link?
• Are you watching videos with little traffic or videos that are private?

There is also the possibility that Invidious makes the recommendations itself, independently of YouTube. Clearing Invidious cookies and all site data should mitigate this, but if you are signing into Invidious then doing that won't accomplish much.

Additionally, Invidious may make the recommendations based on all its users' activity. If you're using an instance with little activity then the recommendations may be more heavily skewed to your activity. There's also the possibility that other users of your Invidous instance share interests with you.

Lastly, it is also possible that YouTube's recommendations are based on unrelated factors.

• YouTube may be recommending videos because they are genuinely popular or are trending in your area.
• YouTube may be recommending videos based on other users' YouTube activity on your IP address.
• YouTube may be recommending videos based on other internet traffic YouTube/Google/Alphabet has associated with your account, fingerprint, or IP address.

All of this, including several other possibilities not mentioned, is far more likely than Framework shipping a hardware/firmware backdoor that hasn't been caught yet which allows Framework to monitor your Invidious acitivity so Framework can sell/share your data back to YouTube. This is a very niche use case that would be extremely expensive, difficult, and risky for Framework (or any other computer manufacturer) to accomplish. Any money Framework makes from this would likely not even cover the cost to do this.

The Framework "backdoor" that you heard about is likely the data breach that recently impacted Framework. This data breach occurred due to a phishing attack on an employee of the accounting firm contracted by Framework.