I mean thanks to bridgy you can communicate across blusky and mastodon. For example people can follow my mastodon account on bluesky.
And bluesky has gained > 8 million users in the past couple months. Mastodon has 900 odd thousand MAU.
So clearly the majority have gone to one.
Even if your numbers are true. Mastodon has existed for 7 years. Bluesky for less than one.
So logically the precentage of users to active users should be much higher on Bluesky.
Also number of accounts is possibly a bad metric to judge mastodon because of the federation.
For example, I have 8 mastodon accounts (tried a couple different instances and programmed a couple rss bots to give me a news feed).