125k is entry level for FAANG, but most jobs aren't. I got offers from mid sized companies in the BA, 140k max with +10 years of C++ experience, I guess that qualifies as Senior? +relocation package, green card sponsorship, etc, but still very much not worth it.

125k at FAANG is base. With bonus and RSUs that becomes 160k+.

140k is a very low offer for someone with 10 years. Offers like that are typically made by desperate startups.

Seniority is assessed by skills and not tenure. Requirements for senior positions are pretty stiff in Bay Area. Seniors need to deliver regarless of circumstances.

>140k max with +10 years of C++ experience

Ouch, that feels very low to me. Granted, I'm in Boston, but you can get that at nearly any startup around here (I've both held those jobs and hired people for them). The bigger companies can then throw some real equity on top of that.

Wow, so high! What kind of engineers are mid-level or senior? Typically, is a lead engineer a senior?

Mid-engineer is someone who can accomplish all tasks with occasional design-level guidance. Senior is someone who can accomplish complex tasks without any guidance.

Lead is a senior engineer.