This is about 7% of all their employees.
People report that a lot of QA, security, and release management folks were sacked.
A lot more details in the TechCrunch article: https://techcrunch.com/2020/01/15/mozilla-lays-off-70-as-it-...
> In an internal memo, Mozilla chairwoman and interim CEO Mitchell Baker specifically mentions the slow rollout of the organization’s new revenue-generating products as the reason for why it needed to take this decision
edit: fixed the numbers, added some more details.