Are you sure this isn't any addon causing this?
Because ZOs said they disabled that auto resummon:
https://forums.elderscrollsonline.co...august-29-2023
Maybe it got fixed and re-enabled again meanwhile.
The part about No interact makes no sense to me btw. The addon should disallow interaction if you move your corsshair above the companion and press the use key but not summon/unsummon via a quickslot afaik?
Did you check the other companion related addons already? I'm pretty sure one of those got 1 keybind to unsommon "currently active" companion, so it would be 1 keybind to add then.
Maybe they even have features to prevent the auto resummon that ZOs introduced already.
Just search for "companion" with the addon search.
e.g.
Auto Banish Pets/Assistants/Companions
btw:
Install the addon EMACs to get keybind support with additional key combinations like SHIFT, ALT, CTRL
It's discontinued and outdated buts till works, you just have to manually install that.
Or install the chat related addon pChat e.g., it includes the same.