Any rollback of free food perks is a bad sign. It's not always a sign of bad health, but if it's not it means the company is softly lowering the status of it's rank and file in order to put in another layer of management.
Weekly lunch for a whole company isn't a huge deal at a startup, and it's not going to shorten the runway much. But when you've suddenly got 10x or 100x the original employee count it starts to look less pleasant. By the time a company is spending several salaries worth of money on free lunches, it probably looks tempting to cut them. (And it's probably less destructive when everyone knows the finances are going strong.)
But I feel like I've seen both sides: Growing out of childhood and falling into senescence. The next time I see this pattern, I'll leave a couple years earlier.