Recent exceptions:
1) Chrome in Android has recently begun to hang when trying to go back to a previous page. It's gotten so bad that I end up clicking multiple times, which all register in rapid succession. If I click more times than the history depth for the tab (say 3 or 4), I end up back on the home screen and a lost tab with lost (or at least not conveniently recoverable) history.
2) AMP. When Google began pushing AMP my objections were mostly based on principle; performance was mostly a wash for me. Now the AMP viewer is so slow and so crash prone that I'm conflicted. On the one hand, I'm glad to see that AMP is clearly failing. On the other hand, Android and Chrome still strongly favor AMP, and I'm too lazy to wrestle with Google over default settings, so when I don't have the presence of mind to explicitly open a web site (e.g. when using Google News) I'm left to suffer the poor performance and bugginess in addition to other intentional AMP headaches--lack of copy+paste, less scrolling and zooming control, etc.
Not quite the same thing, but related, technologies like QUIC are really only beneficial in the context of a web ecosystem built by Google. QUIC shines on websites pulling in many resources from disparate hosts, which in most cases is a situation created by advertising and analytics services. IOW, these days much of the benefits of Google's work simply pays down the debts Google itself created or advocated. And while Google still stands out for the amount of labor it invests in open source security and performance, it's just a matter of time before we pass break even into negative return territory. That happened long ago with Google Search itself; Google Search results are as slow, irrelevant, and obscured by obnoxious and misleading advertising as the competitors it originally, rapidly displaced. Heck, when Google began those investments (Android, Chrome, OS security, etc) they were crystal clear why they were making them--to nurture and grow an ecosystem into which they could grow their advertising business, same as their rationale for making a snappy search service and a non-intrusive advertising network. There's a limit to how well they can improve that ecosystem, but the limit for exploiting that ecosystem can easily result into a situation far worse than the one Google originally saved us all from.
Consider why rendering work is even relevant in 2021. It's not for the benefit of services like Netflix or YouTube, which already enjoy low-power hardware acceleration, and arguably not for games or similar interactive content. It's so they can continue shifting their advertising ecosystem from minimalistic text-focused display boxes to animations and videos peppered up, down, over, and under content views. They can't do that if advertising-laden web pages drain your battery in 15 minutes, as notorious Flash-based ads once did. Steve Jobs' famously removed Flash from mobile; Google, for obvious reasons, is taking the alternative path.