Not necessarily. It depends why they were primarily successful on TikTok, which we don't know. If it's because American platforms tend not to highly rank content that goes against the US's geopolitical ideology, then no, I wouldn't expect that.
Leaked data reveals Israeli govt campaign to remove pro-Palestine posts on Meta - https://news.ycombinator.com/item?id=43655603
Meta: Systemic Censorship of Palestine Content - https://text.hrw.org/news/2023/12/20/meta-systemic-censorshi...
Facebook has severely restricted the ability of Palestinian news outlets to reach an audience during the Israel-Gaza war, according to BBC research - https://www.bbc.com/news/articles/c786wlxz4jgo
To be a first amendment violation this would technically have to involve the US government working to censor American's speech over Palestine. Functionally, though, this is a government censoring specific speech and feels very much like a free speech issue.
Another thing we know is that the White House under Biden was pressuring FB and others to downrank anti-covid-vaccine content until a judge ordered them to stop.
Kind of quaint in 2025.