Yes. Without a subscription, cams are limited to uploading a Thumbnail Image every 5 minutes. With Cam Plus Lite on compatible cams, that increases to a 12s video but still has a 5m cooldown.
There is no way to say for sure why the two cams were previously getting the 12s videos unless they were subscribed to Cam Plus Lite. There have been reports of cams that were previously on the “Legacy” plan, which included 12s uploads prior to the subscription change, remaining that way until some account or update randomly corrected them to Thumbnail images.
New cams without a subscription will not get any video uploads. Old cams were all supposed to be transitioned when the subscription tiers changed, but there have been reports of stragglers.
Coming up on 2 years ago.