The custom domains issue is a real problem. Nowhere in the description did it say that the plan will allow only 1 custom domain. It was plural. The expectation for Sumolings was that there would be unlimited cistom domains on the Pro plan, as in a custom domain per QR code.
As an agency, using the Folders feature to organise QR codes for clients, and expecting to be able to create a custom domain per client (folder) can't be done.

It's a real limitation and makes this a negative experience for an otherwise good product. Unfortunately there seem to be few, if any, QR saas that get this right and it doesn't seem like a difficult thing to get right.

You have also stated in other replies that "soon" the 1 custom domain limitation would be increased to 5. That was a year ago and the quota still has not been increased. When will this happen?