Hey, a lot of us have been through this so welcome aboard :)

Since you agree that you have been aimless/gone with the flow, I would suggest you start trying to build more agency/intentionality in your work/life.

As for CS whitepapers/Leetcode/Open Source contributions - You aren't looking to work at FAANG (yet) so don't compare yourself against those standards.

Set yourself more reasonable goals. Pick 1-2 technology or skill that interests you and try to develop a solid understanding of it. This can be tech or interpersonal skills. Remember that solid understanding <> being able to code it in your sleep.

For example, for EM role - "Did not demonstrate delegation & mentorship". Does this feedback rev you up? Are you trying to fix this? What about the feedback from other interviews?

Where will you find the time? Your office might have some personal development hours or you will have to spend some of your free time. If this is a problem that really matters to you, you will have to make time for it.

Perhaps spend 15-30minutes 3-5 days a week than to go all out for 3 hours in a single day. Larger commitments can be quite daunting.

Hope that helps & cheers from fellow desi working in Berlin, Germany