Oh I’m a pro at gravy since I hate the canned stuff. Key is watch the temperature and slowly add thickening using wire wisk.....I pre-mix before adding unless making pan gravey. That requires high temp to brown drippings first then add flour and brown, stirring constant then water or milk.
Alos low boil the gravy for a time which will remove the flour taste.
So, you use flour, not cornstarch? I’ve never had a problem making various sauces with fat, flour and stock; but cornstarch seems trickier.
We’ve been using arrowroot powder for gravies since my mom got the idea from Graham Kerr.
It also is gluten free and my son recommended it to a guy he worked with who had celiac and they gut told him that he now basically got his life back. He could eat Montreal Fries again.