I think the program was legal and morally fine.
Take into account that these are corporate computers, and the tracking is of work that the company is paying for, so the telemetry, which is highly valuable for analysis and automation, is rightfully theirs.
I also don't think that the purpose of the move was to manage workers and see if they slack off, it was to gather training data, but even if it were, I think that's normal? In any other job managers can, and are expected to, monitor employee productivity, they are paying for it, they need to ensure they are getting something worth. But again, I don't think that was the main goal here.
The computers are not intended for personal usage, if the employee wants to watch netflix, or porn, they are free to do so in their personal computers.
Imagine if this were a construction company, and there's a foreman watching the employees output, and the machine operators have their actions logged so that the machines can be automated in the future. Doesn't it sound reasonable? Is this very different at all?
So yeah, maybe a lot of people see Meta and computer tracking and immediately jump to 1984, but I kind of like nuance more than knee jerk reactions, or jumping into a narrative that we enjoy being angry about.