I am not having any big issues using EyeTV 4 (8531) on an M2 Pro Mac Mini running MacOS 13.6.1 with an (ATSC) EyeTV Hybrid USB stick. I will not be moving to Sonoma anytime soon; I am a late adopter.
EyeTV 4 is a separate purchase, not a free upgrade, from EyeTV 3.x. For me, EyeTV 4 works well enough. Some people posting here seem to have many issues. I found that it was VERY important to use the no-cost EyeTV Reporter tool (available from Geniatech.EU) to remove all traces of EyeTV3 BEFORE I tried to install EyeTV 4. Making backups before doing the upgrade is always sensible, as with any upgrade.
(Aside: I strongly suspect El Gato built EyeTV 3 on the CARBON interface, which was deprecated when MacOS moved to 64-bit. I believe GeniaTech had to do a lot of work to rewrite the 3.x software to support the COCOA interface required with a 64-bit MacOS.)