How Signal is still working?

I was searching for the place of Signal’s headquarter and i found that
Signal’s revenue (2020)
And its expenses (2020)

So how are they covering the gap between their revenue and their expenses??

Source: Signal Foundation - Wikipedia

Probably the $33 million they still have in the bank according to those filings.

They have sarted to ask for donation a few years back. So I guess they are trying to make this more sustainable Signal >> Blog >> Become a Signal Sustainer