I've been looking into this recently (I'm thinking of getting one, and the subscription had put me off previously). As far as I can tell, there was originally no subscription, then they introduced it, I think with the Remarkable 2, with a basic subscription offering infinite synced storage, and a higher tier subscription offering a bunch of additional features like screen share and handwriting recognition.
They've done removed the higher tier subscription, and all of the additional features are available as standard with the device itself, no subscription required. The infinite storage, however, still requires a subscription, but only the basic tier (3€/month, I think).
Tbh, it makes me lose a certain amount of trust in a company for trying that sort of "pay for extra features" thing out, but they've withdrawn most of it and I think the current approach is significantly more reasonable. And as you say, it's still a Linux device in the end, so you've got a lot more flexibility than you might on other devices.
They've done removed the higher tier subscription, and all of the additional features are available as standard with the device itself, no subscription required. The infinite storage, however, still requires a subscription, but only the basic tier (3€/month, I think).
Tbh, it makes me lose a certain amount of trust in a company for trying that sort of "pay for extra features" thing out, but they've withdrawn most of it and I think the current approach is significantly more reasonable. And as you say, it's still a Linux device in the end, so you've got a lot more flexibility than you might on other devices.