why do this look like a page of sonichu?

Never heard of Sonichu, but if you mean the background colors, we're color picking off a Gold/Silver/Crystal screenshot. If they're doing the same, that may be why

may also be the overlyabundance of speech bubble suffocating the picture and the choice in font that parallel said comic

Not seeing the speech bubble thing when I search for Sonichu, but the crowding is an effect of "this is where the rules are explained, kind of need a wall of text for them even if there is just a couple of them..." and is becoming somewhat of a tradition (cf my first shrink drive https://www.furaffinity.net/view/51620781/ ).
Most pages in the series won't be this crowded

Font is definitely different, his has sharp edges!

they're both comic sans