Well, yes. It’s almost all of their annual revenue and Mozilla already had huge layoffs[0], so presumably they’re not exactly on amazing footing financially. Duckduckgo could not provide anything near that much - ddg has 100m in annual revenue and Google is giving 500m to Mozilla. 5x their entire company’s annual revenue.
If an organisation can be in financial trouble with an annual income of half a billion then it's poorly run. That's ample resources even for something as complex as a browser.
[0] https://www.theverge.com/2020/8/11/21363424/mozilla-layoffs-...