GPLv2 requires you to either distribute the source with the binaries, or provide the recipient information on how to obtain the source code. It also states that providing a link to the source code next to the binary download on your website is sufficient. See GPLv2 section 3 for more details.

TikTok have not provided a link to its source code, not are there instructions on their site or within the download package indicating where users can obtain the source code. Therefore, it's a violation.