World Princess II is a possibility. Kill v Maim is also a diss track about a lot of things, which may include producers. My interpretation of Kill is that it is Grimes throwing some well deserved shade on her former manager and label head (and mixer- if not producer) Seb Cowan. The song seems to be a vicious parody of Cowan and his way of running his "underground" (see: video) indie label Arbutus as if he is a small time gangster, which included (still includes, actually) not paying Grimes any cut of the profits from her own music, expecting her to make posters for his label and put them up each day in the harsh Montreal winters without even the pay to eat an avocado, setting extreme deadlines that force her to do speed and stay up continuously for two weeks to finish her album, and forcing her to tour constantly at risk of collapsing and dying on stage, all while exploiting her sudden fashionability to get rich and promote himself and his label, but disrespecting her, poorly managing her career and leaving her at the mercy of creeps (the infamous "kiss rapist" for example) possibly even worse than Cowan himself. The only solution was of course to fire Cowan as her manager, leave Arbutus and sign with Jay-Z's management team. For this she was probably attacked as a sellout by Cowan, who continues to make money from reissuing vinyls of her work (zero money goes to Grimes- don't buy it- find a used copy if you can- or just avoid buying her first two albums on vinyl, she intended them to be heard digitally anyway when she made them, and she had no say over the sound or look of this vinyl).

ps. Pls bear in mind, she was not dissing the existence of male producers in general. obviously she knows several on a personal level as friends and respects them professionally too- e.g. Bloodpop who she recently tweeted to congratulate after his song with Justin Bieber, Sorry, hit #1 on hot 100 charts. she even worked with Bloodpop (long before he was doing Bieber tracks) in a rare exception to her rule of producing everything herself- just because they are old friends from both of their pre-fame days and she likes his musical approach (and those tracks, Go and Phone Sex, also were only intended as singles- not parts of her albums). when she called out male producers, she was calling attention to the structural inequality within the industry i.e. there are basically zero female producers getting regular work, which owes largely to the misogynist culture in labels and studios. one of the absurdities that results from this, is essentially every single song any of us likes (or dislikes!) was in fact, "produced" by a man, at least when considering major label releases. so obviously she respects the work of many male producers if she likes music. the problem is why are the women who are producers being marginalized? well, here is one reason- she was also dissing many specific male producers who have hit on her or make assumptions she needs their "help," when she is in fact a better producer herself than any male (or female) producer now in the business. many other female artists who encountered this may have just given up, but not grimes. as she noted, most of the people who offer to "help" her (and "produce and chill?" is basically code for "reproduce and chill" most of the time) are not even particularly talented producers in their own right, so it's doubly insulting. she might feel a little more cool about it if it was Trent Reznor or the ghost of David Bowie and Michael Jackson asking if she wanted to collaborate or something.