>4. A dwindling marketshare percentage does not directly imply old userspe are moving from Firefox to another browser, it could imply that new users don't know/use firefox
You're right that it could theoretically mean that, but unfortunately monthly active users have actually fallen by ~20% since 2019 according to Mozilla:
It may also just mean more users are opting out of telemetry. Given Mozilla's privacy focus in their marketing and their UX, it may not be a shock that a large number of users are also opting out of even Mozilla's telemetry.
You're right that it could theoretically mean that, but unfortunately monthly active users have actually fallen by ~20% since 2019 according to Mozilla:
https://data.firefox.com/dashboard/user-activity