Bit of a dumb question, but is there a reason why you only use mirrors, rather than itch.io itself? both mega and Gdrive has traffic limiting issues.
For instance Gdrive is currently locked do to the amount of traffic and this is a reoccurring issue there.
Mega on the other hand you need a subscription for due to the sheer size of the game being bigger than public download limits.
These seem to limit the games potential player limit to some degree and likely has cost you some potential traffic due to download limits, something itch.io itself doesn't have that I am aware of.
Maybe I missed something, or maybe itch.io has size limit I am unaware of, but it seems like you would only increase the amount of people able to play if you added it to itch.io directly rather than using mirrors.