I tried going almost meat free for a good decade (largely thanks to huel, which allow you to eat enough protein to workout). Everything was fine until I hit 30

I tried going almost meat free for a good decade (largely thanks to huel, which allow you to eat enough protein to workout). Everything was fine until I hit 30s. I started having serious stomach issues that doctors blamed on "stress" or the misteries of the gut. Over two years I dropped huel, gradually went back to meat, dairy and vegetables and grains. I still had painful, bloody and explosive episodes. I started eating a carnivore diet and all the symptoms disappeared in a week. I also lost 7kg. This made me revaluate everything I believed in nutrition. I realised that the reasons for introducing a vegetarian diet as part of USDA was pretty much baseless and that USDA backpedaled on fat consumption being bad. At this point I frankly doubt much of the research on nutrition and I'm not sure if I buy the reasons to avoid meat. Is there really a link between meat and cancer and cardio diseases or are you just trying to sell me some preprocessed vegan crap?