Interesting, this reddit thread from a number of years back says something very different about Canonical and salary negotiation. Who knows what happened in the background in your case:
"all coworkers i've talked to who are comfortable with talking about salaries have said canonical is their highest paying gig to date. each employee salary is negotiated and some have a lot more perks than others. without going into any detail canonical provided a significant salary bump over my previous position."
https://www.reddit.com/r/Ubuntu/comments/oiqbt/ask_rubuntu_h...
"all coworkers i've talked to who are comfortable with talking about salaries have said canonical is their highest paying gig to date. each employee salary is negotiated and some have a lot more perks than others. without going into any detail canonical provided a significant salary bump over my previous position."