Roku gave me a number to call Acorn support. It turned out to be Acorns investments. Finally found a way to reach Acorn support and learned Roku support was also lying that Roku does not control content:
Dear Subscriber,
Thank you for contacting Acorn TV!
We can confirm Acorn TV is a commercial free streaming service. However, if you are streaming from a third party device such as Roku, Amazon/ Firestick, Apple TV, FireTV etc. Roku's have recently started showing interactive pop-up ads overlaid.
At anytime we recommend to stream Acorn TV on all standalone apps via our website or mobile apps, and iPad/Tablets.
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The Acorn letter also includes a link to a gizmodo article Your Roku is an ad factory, but this forum does not allow the link.