First you allow backup for free and then you suddenly take money for my own data? I will complain about your tricks at mozilla.

Hello

I don't understand you. Local backups are free. We dind't change it.

Well "Friends of Mozilla" - why don't you complain to Mozilla about with every update of theirs they force the mandatory changes upon extension developers also, because Mozilla does not give a heads up in details to those developers that create the extension for FREE.

I am NOT associated with Nimbus at all - 

but I am a user of FVD and sync also as long as they exist. And have bin frustrated with updates. But, every time it turns out that Mozilla is not held accountable of their silly small updates, just to push 'update' to the users, making it look like that they are working really hard. That may well be so - 'but' they have never cared about the developers that create free extension, we all so happily use. The FVD is FREE always and so is the basic sync function it draws exclusively from the file in mozilla to sync. All that is FREE. 

But if you want the sync and restore function they have on their server and you want to use that restore versus your own - then YES you pay a measly 4 or 5 dollars for the bandwidth and storage it takes to keep YOUR stuff safe. Just in case your computer crashes or firefox becomes irrevocable useless and you need to start from scratch - that is the insurance you would pay for but it is NEVER mandatory. If you signed up for that at the beginning, and unless you CANCEL this feature, yes you will be charged as per your own agreement.

Not to mention an apology is in order to the team of that extension. No matter how frustrated you are, there is no reason to be that crude.

I run an art gallery online since 1993, with nearly a thousand members. I have not ever encountered such strong language as yours.  I bother to write this long clarification simply because I am grateful to be using, in particular, this extension now for years and always for free. The server part - yes is a paid offer. If you don't want to pay for it, then just go and cancel that part. It's rather simple.