I have a hard time believing that since TikTok is such a popular mobile app, and 4G users are going to have a minimum of 200ms latency over-the-air.

5G does offer much faster over-the-air latency of only 1ms, but if TikTok were to become unusable if the latency between tower and server exceeds 1ms, I would expect to hear widespread complaints about that, as the vast majority of users aren't going to have <2ms latency between them and the server. Pinging TikTok.com from my 5G handset (in a major metro area) shows a latency of 80ms. Admittedly, AWS and GCP, where TikTok hosts content primarily for US users, likely has better latency. My personal experience with those platforms doesn't suggest that it would be that good- pinging the cloudfront CDN endpoints associated with my account, I get latency between 40-60ms.

Besides, video streaming shouldn't be affected by latency, only throughput. TikTok videos are just MP4 files on a CDN, as long as you can download them faster than you can play them, high latency shouldn't even be noticeable to the user, outside of initial load times for latency exceeding a few hundred ms (up to a second or so delay if establishing a fresh TCP connection, depending on the latency).

Maybe TikTok Live could be an issue, but its a one-way channel so a delay shouldn't be noticeable like it would be with a 2-way teleconference. Maybe if there was high jitter or packet loss, the stream could have extremely low quality.