The concern, I think, is that their spare cash is dwindling and thus financial prudence might be beneficial - especially for those who rely on the core Mozilla propositions like Firefox.
The last I heard was that the Google rev-share agreement was on the skids and they stopped developing projects like Thunderbird and Fake Spotter because they were capital constrained.
If you know otherwise then you're better informed than I am I guess
This might be financial prudence of sorts - doesn't something like 80% of their yearly monetary contributions come from Google, particularly for search partnerships? If they are concerned that Google will start paying them less because search has diminishing future returns, diversifying their income sources through investments in AI might be a good idea.