it will cause problems if your channels are spam or low effort content, that is why you need to follow isolation method, creating multiple gmails with different numbers, using proxies and etc....however if your channels are all high quality and you do everything else right that is choosing the right topics, create hq thumbnails and keep the retention rates consistent, youtube will kind of whitelist your channels, because your channels are valuable to them at that point...but this is achieved rarely by creators while they scale. There also may be the issue of one channel getting de-monetized and then youtube just de-monetizing or shadow banning the rest of the channels as well. So best is to keep 1-2 channels linked to one account.
Hope this helps..Goodluck!