How can I deal with promotion if no senior engineers in the team

Check out this previous question about SDEII => SDEIII at Amazon!

Although not a direct 1:1 correlation to Amazon, but I got my senior level promotion at Robinhood when my teammates were nearly all mid-level engineers during the stringiest year Robinhood had for promos (we did 2 mass layoffs that year).

The reason why I felt like I got the promo was:

1. My manager believed in me. If your manager doesn't believe in you, it's nearly impossible to get promoted to senior. Your manager is the one who is putting you up for your promo: you can't get promo'd if they never put you up for promo.
2. I contributed more than my peers by multiples (at least 1.5x more lines of code merged in). As a result, I was given opportunities first because I was more efficient. It also helped that I barely took any PTO during that time, so opportunities naturally came to me while my peers were OOO.
3. I took on things that no one else was taking up. The main example is I took a large detour once to led a high-priority SEV no one was able to successfuly debug after months (we even had a staff engineer leading the SEV, and they weren't able to root cause). I both established structure on how we'd proceed with closing out the SEV and eventually being able to root cause it 2 days after taking over as the owner. This stood out because no mid-level engineer had closed out a SEV of that complexity (so this greatly stood out on my perf packet).