Kanye West has expressed, very publicly, his discontent over his and Kim Kardashian's daughter, North, being on TikTok -- but we're told ... the 8-year-old can't even log on without mom's permission.

Sources close to the former couple tell TMZ ... North doesn't have her own TikTok account, nor does she have the app on her own phone any longer. Instead, we're told North can only access TikTok through a joint account on Kim's phone -- and only uses it in her mother's presence.

Not just that ... but our sources say the comments for North and Kim's account are fully disabled. We've even spoken to sources at TikTok who tell us ... North and Kim's account passes the company's terms and conditions for minors.

Now here's why Ye might be in a tiff over this ... according to another source in the know. We know there was, in fact, an incident recently where North did go live on TikTok from her own phone -- but our sources say Kim disciplined her over that and made the changes then.

We're told Kim, Kanye and his cousins even had a discussion over the incident, and they agreed to the new parameters that North is now confined to ... aka, no social media on her phone, and only being able to hop on through her mom's account with her mom there too.

With that said ... our sources say it's confusing to Kim that Kanye is making a big fuss about North's recent video, because she thought everyone was on the same page from before.

As for why an 8-year-old would even have her own phone ... sources close to Kim tell us it's so she can have a direct line to her dad, and vice-versa. Of course, we're told that phone is fully monitored with all the parental blocks you can imagine -- and to reiterate ... there are no social media accounts on it at all.