Have had similar problems on my Roku Ultra. However, as of today, the problem is on Hulu and Disney+. Seems to now be affecting everything that Roku displays instead of just the Hulu show I'm watching. This is very frustrating and nearly unwatchable.
I am having the same problem! It is extremely frustrating I am using a Roku Express on an RCA TV. I have changed the display settings from auto-detect to 1080p and then to 720p, and neither stuck, the program was fine until an ad came up and then it zoomed. I am only noticing it on Hulu at this point. I wish Roku would acknowledge this thread and fix it!
I also have zoom in issues while watching One American News. I have a Roku 3 and a Roku 3810x stick and both have the same issue on two different TV's. Have a smart TV and it is fine. Issue started first of the month (7/1/20) software 9.3.0 4170-04. Does Roku support read these post and act on our issues or is posting here just to make us think they are interested in helping their customers?
I reported this problem to Hulu. The person I spoke with told me this is a problem they are aware of and said it seems to be happening primarily with 3900x Roku Express models. I also have a 3500 Roku Stick and I have not seen the problem. I deleted then reinstalled the app, unplugged the Roku, etc. and nothing helped, except changing the ratio on the Roku to 1080p. So far it is working, but I noticed the issue with the ads cutting off early still happening. I guess the only good news is Hulu is aware and working on it.