The issue with "senior" in tech is that it has two different meanings. You can be a senior engineer in the sense that you've been in the industry for a long period of time and have the kind of deep expertise and understanding that only comes with having spent a long time immersed in something (you've seen some shit), but that's entirely different than having a job title of "senior engineer."
For example, at the SF-area non-FAANG unicorn I work at, if you are L5 then you are considered a senior engineer by virtue of your job title, but when the directors and heads of XYZ department refer to the senior engineers, they mean L6 (staff engineer) and above.
FWIW, my own opinion is that if you have less than 10 years' experience, you are not a senior engineer, regardless of what your job title says. You might still be a complete superstar and understand algorithms inside and out and be able to produce efficient, bug-free code that compiles on the first try, and that's great, but there is no substitute for the wisdom learned over time, particularly if you're going to be expected to deal with people as part of your role.
For example, at the SF-area non-FAANG unicorn I work at, if you are L5 then you are considered a senior engineer by virtue of your job title, but when the directors and heads of XYZ department refer to the senior engineers, they mean L6 (staff engineer) and above.
FWIW, my own opinion is that if you have less than 10 years' experience, you are not a senior engineer, regardless of what your job title says. You might still be a complete superstar and understand algorithms inside and out and be able to produce efficient, bug-free code that compiles on the first try, and that's great, but there is no substitute for the wisdom learned over time, particularly if you're going to be expected to deal with people as part of your role.