I used to work for them. I still found that I have a $300K ceiling.
That's literally impossible. What level did you get hired at? I'm assuming at least 5 given your background/exp? That's more than 300k EZ unless you're talking about salary only.
Google lvl 5 total comp is ~$320K. So it is pretty close and still less than PHP consulting.
Aren't there ranges within the levels? I know of people receiving offers of more than $320k at T5 and equivalents beyond Google.
If you have 10 years of experience practicing ML, AmaGoogFaceSoft would be falling over themselves to pay you $300k+ in total compensation.
Whether you'd want to move to SF/NY/Seattle and work for them, though, is another question!