Not sure where you got the idea that the core development team has been cut, Firefox development remains strong. For example, here's a 1,000+ line patch that just landed two days ago.
https://bugzilla.mozilla.org/show_bug.cgi?id=1779952
That's not the core dev team, at all. Servo was a research group, building an experimental browser engine, parts of which did end up transitioning across to Gecko.
https://www.protocol.com/amp/mozilla-layoffs-2646950077