I am thinking it may be the HDMI version and included HDCP version (the content protection scheme) of this switch that may be giving you issues with the Ultra 4660.
Is the message you are receiving being produced by Roku re: the need for a better cable to receive a better picture? Does it look similar to this message from this Roku support article regarding HDCP 2.2 - https://support.roku.com/article/230317588?
If so, and you are trying to watch 4k/HDR content, the HDMI 1.4 (HDCP 1.4) may be the culprit and the Ultra should default to 1080. Try lowering the resolution in the Roku settings to 1080p and see if that helps with the static/fuzziness. Settings/Display Type/1080p. [do not use autodetect, manually select 1080p).
If the above resolves your issue, then you can try looking at the the SGEYR HDMI switches that supports HDMI 2.0 (HDCP 2.2) if needing higher resolutions. These will be backwards compatible with HDMI 1.4, but also support the newer standards.
This is the link to to SGEYR store on Amazon. https://www.amazon.com/stores/page/E84DDB38-7327-462D-98A0-8FE2E323BBBB?ingress=2&visitId=0594329a-e...
(just look at the HDMI switches that indicate HDMI 2.0 (HDCP 2.2). They have one for 19.99, 23.99, and 45.99.
If the above did not resolve your issue, try using any 4k HDMI cable. (ie. https://www.amazon.com/AmazonBasics-High-Speed-HDMI-Cable-Black/dp/B08BS29VG4/ref=sr_1_6?keywords=hd...). Don't bother spending a bunch of money on a HDMI cable. Many inexpensive ones will work just fine for Roku devices. (some very cheap ones may trigger some HDCP errors but since you are not currently experiencing that, I wouldn't worry about it at this point.)
Also post the model number of your TV if you are still having issues after trying the above so we have complete understanding of your setup, what type of content (display resolutions and channels/apps you are trying to watch as well). Also post a screenshot of the message you are receiving if it does not match the Roku message indicated earlier in the thread.
Roku Community Streaming Expert
Just another Roku user... I am not a Roku employee.
Insignia RokuTV, Ultra 4660x, Premiere+ 3921, Express 4k+ 3941