This post is somewhat inspired by a recent post in this same community called "Is anyone else having trouble giving up Reddit due to content?"
I imagine "Reddit" will be a common answer. (And it's one of my answers.)
Another of my answers is "Hasbro." First Wizards of the Coast (a Hasbro subsidiary) tried to revoke an irrevokable license and screw over basically all 3rd-party publishers of D&D content, then they sent literal mercinaries to threaten one of their customers over an order mixup that wasn't even the customer's fault. D&D: Honor Among Thieves and the latest Transformers look really good, but those are within the scope of my boycott, so I won't be seeing those any time soon.
Third, Microsoft. (Apple too, but then I've never bought any Apple devices in my life, so it hardly qualifies as a boycott.) Just because of their penchant for using devices I own against me in every way they can imagine. And for really predatory business practices.
One boycott that I've ended was a boycott of Nintendo. I was pissed that they started marketing The Legend of Zelda: Breath of the Wild (though it didn't have a name at the time) before the WiiU came out, prompting me to be an early adopter of the WiiU, and then when they actually released BotW, they dual-released it on WiiU and Switch. I slightly eased my boycott when the unpatchable Fusee Gilee vulnerability for the first batch of Switches was discovered. I wanted to get one of the ones I could hack and run homebrew on before they came out with a model that lacked the vulnerability.