Google changes its server-side logic frequently. Even if you get 15.21.1 working today, there is no guarantee it works tomorrow. You might open the app to find an error message saying "Update Required" or "Login Failed."
Use Brave Browser for iOS. Open youtube.com. Brave blocks all ads on YouTube by default, even on iPhone. You lose background play, but you gain safety.
Do not download from random pop-up ads. Stick to these GitHub and archive communities: youtube 15021 ipa download upd
For the average user? No. The hassle of refreshing the app every 7 days, dealing with potential crashes, and missing out on modern features (like proper 4K HDR support on newer chips or the latest UI changes) isn't worth saving a few dollars a month.
For the enthusiast? Yes. For those who remember the golden age of iOS customization, version 15.21.1 represents a functional artifact. It is a testament to the community's refusal to accept the ad-laden, restrictive default experience. It offers a clean interface, no ads, and a sense of control that modern apps have stripped away. Google changes its server-side logic frequently
Google is aggressive. If you use a modded IPA that blocks ads, Google may send a warning:
"You may have been using a third-party app that violates YouTube's Terms of Service." Use Brave Browser for iOS
You have the youtube_15021.ipa file. Now, how do you install it on an iPhone or iPad without jailbreaking?
The keyword includes upd (Update). This implies you already have a version of the YouTube IPA installed and need to upgrade it to 15021 without losing your data or modded settings.