Honestly, this may not not be a failure on your part but perhaps on your manager. As an employer, I found myself guilty of this until I noticed that the reason junior devs on my team were underperforming was because of me.
There is a misconception particularly about startups (and I'll be the first to say I was living under the same rock) where they're seen as a magical box where you put a junior developer in on one end and they automatically turn into a seasoned vet on the other end. Yes, this may happen and you definitely will ramp up in terms of skills (both technical and people skills besides learning how to operate as a creative professional, etc) but it requires effort on your employers/managers part too—training, one on ones, feature planning, talking about how you would build before you actually do, what you're building and why, and how/why architectural design decisions were made, etc.
If you find your self out of your depth and in positions where you have to make senior dev decisions with no context or idea how to make them and why you choose the outcome, your management has failed you and perhaps themselves as the outcome will likely harm the team/company more than it will harm you.
There is a misconception particularly about startups (and I'll be the first to say I was living under the same rock) where they're seen as a magical box where you put a junior developer in on one end and they automatically turn into a seasoned vet on the other end. Yes, this may happen and you definitely will ramp up in terms of skills (both technical and people skills besides learning how to operate as a creative professional, etc) but it requires effort on your employers/managers part too—training, one on ones, feature planning, talking about how you would build before you actually do, what you're building and why, and how/why architectural design decisions were made, etc.
If you find your self out of your depth and in positions where you have to make senior dev decisions with no context or idea how to make them and why you choose the outcome, your management has failed you and perhaps themselves as the outcome will likely harm the team/company more than it will harm you.