First off, if you make a change to a higher fiber diet, you're likely to have increased flatulence while your gut microbiota acclimates. Second, there are different fiber sources that each person may respond differently to. Personally, some legumes will make me gassy no matter how I cook them, but when I throw a serving of psyllium husk in whatever I'm eating, I have no problem.

You may have an intolerance to certain foods. Look up low FODMAP diet. Certain types of food can fermented in the gut and make tou gassy/bloated. Ive found that I dont have an issue with wheat, but switching to lactose-free dairy and avoiding onions has helped me immensely.

Your body gets used to it after a while, although you may still be a bit more gassy than people who shit once a week.

Not particularly to the point that I've noticed any difference though I've heard that can happen. I'm typically only doing 1-2 servings a day despite the bottle suggesting 3-5 servings, so maybe that's the difference.