Facebook participates as part of the NSA spying apparatus. They conducted studies that showed they could alter the emotional state of it's users by altering the content being shown in their feed. They actively engaged in political misinformation campaigns on behalf of the GOP as shown via the Cambridge Analytica scandal. They have direct causal links to fomenting genocide.
Instagram showed from its own internal studies it induces eating disorders in young children (specifically girls) who use their platform.
YouTube profits off the exploration of children either algorithmically or through the monetization of family channels. They algorithmicly promote misinformation and conspiracy.
Snapchat by design facilitates the transmission of unconsentual sexual content. Revenge porn, both of adults and children have been actively shared on the platform in recent years, and due to it's design it makes it incredibly difficult for law enforcement to obtain definitive evidence of it's transmission.
All of these companies harvest biometric information and archive them for resale.
If the GOP was having an honest discussion about the way social media impacts users, they'd be discussing powerful privacy regulations and laws to protect users from these threats. However, they're not. Everything they disapprove of in regards to TikTok and Bytdance is something the American surveillance apparatus has been doing for decades.