• gnome vs genome: 'gnome' isn't actually that old of a word. Some Swiss guy just made up the Latin word 'gnomus' in the 1500s. At that point, /gn/ either was already an invalid onset in English or was very soon to become so. 'Genome' was coined in the 1920s by a German guy, loosely based of a Greek word, so I would guess the stressed \ was interpreted as if it were also Greek and thus pronounced /i/.

• desert vs dessert: 'dessert' comes from Middle French 'dessert', itself from 'des-servir', literally 'dis-serve', as in removing what has been served in order to give you a tasty treat at the end of the meal. Because that initial 'des-' is a prefix, it wouldn't be stressed, thus we have stress on the end of the word. The first vowel may have been reduced to a schwa under continuing influence from French. As for 'desert', that comes from Old French, and while I would expect the ending to be stressed in French, it's entirely possible it was loaned early enough into English that English's native rule of stressing the first syllable took over. The later introduction of 'dessert' would have reinforced this.

• moist vs maoist: Maoist is of course segmented as Mao-ist, and English doesn't have any way to clearly show that, so if Mo-ist was a real word, it would unfortunately also be spelled as 'moist'. Thankfully at least, 'ao' isn't a native English sequence, so that's a big clue, and 'aoi' is not a valid sequence for any single English sound. I think most languages would struggle with this sort of thing, since strong segmenting as happens with neologisms like this will happily defy standard phonological rules so long as speaker can recognize the segments and separate them accordingly.

• flaming vs flamingo: It's a somewhat similar story here, with 'flaming' obviously being the application of -ing to 'flame'. 'Flamingo' is a loan from Portuguese, and English tends to not adapt loanwords to native phonology very much, but that's hardly unusual. Hell, in German, you also have 'Der Flamingo'. Funnily enough though, 'flamingo' is actually related to 'flame'; both come from Latin 'flamma', which entered English via Old French.

• uniformed vs uninformed: Again, another segmentation issue, though it is a kinda fun one. Here, it's uni-formed and un-informed. Both do ultimately originate with Latin 'formare'. Here, the core thing is that 'inform' is a very common and easily recognized word, and we all know that the stress in on the ending. Adding another common prefix to it doesn't distract us from that, especially with the meanings being clearly related. 'Uniform', on the other hand, is much more liable to be analyzed as a single unit, since uni- is not a very common prefix and the connection in meaning to 'formed' isn't super transparent. So, we just treat is as a single largely independent word and that's that.

• laughter vs slaughter: God damn it, you really had to bring \ hell back at the end. So as before, we get /f/ at the end of 'laugh' due to there not being any other consonant around to compensate for totally dropping the . Now, the obvious question is, why doesn't this apply to 'slaughter' as well? That's because 'slaughter' isn't actually a native English word at all. Again, we can blame our friends the Vikings for bringing 'slaughter' and literal slaughter to England. The Old Norse form was 'slahtr'. That first element, 'slah', is actually the same word as English 'slay'. So basically, there never existed an English word 'slaugh' that had that pronounced , and so to whatever extent it was pronounced in the Old Norse word, it could easily fade away without causing problems. Whereas for 'laughter', this is easily analyzable as 'laugh-ter', and since 'laugh' developed an -f ending, 'laughter' kept it in order to maintain consistency.

Truly, what a mess. Beyond sating some curiosity though, I hope this does go to show you that English really isn't total random chaos like it's often portrayed. Every apparent exception or weird spelling has a very real explanation behind it that tells a truly incredible story about an island that saw some Celts settle down, the arrival and then departure of the Romans, a violent conquest by the Anglo-Saxons, continued influence from Christianity, centuries of conflict with the Scandinavians, yet another conquest by the Normans, continuous cultural exchange with the rest of Europe, an explosion of Greek and Latin terms - many coined - during the Renaissance and Enlightenment, and then the modern age of globalization (and colonialism) that's resulted in the importation of words from all across the world. Every word is a story; you only have to take the time to read it.

(the English vowel system is actually insane though; I really cannot defend it lmao)