I’ve seen many threads suggesting products but they often don’t mention FOSS projects, which should always be preferred to corporate software. With FOSS you are already boycotting capitalism, on either side. Free and Open Source ignores borders and shouldn’t be categorized in nationalist terms, no matter where some of the maintainers happen to live.
I think it was US OFAC sanctions
https://www.linuxfoundation.org/blog/navigating-global-regulations-and-open-source-us-ofac-sanctions
https://www.theregister.com/2024/10/23/linus_torvalds_affirms_expulsion_of/ (links to the OFAC sanctions set up after Russia invade Ukraine)
The OFAC sanctions do have quite a few lists, with one of them being “Russian Harmful Foreign Activities Sanctions”, so it could be fear of harmful actions and not just retaliation for the invasion