Most liberal and conservative years of the 21st century?

2002 was the most conservative, without a doubt. That was when EVERYBODY supported Bush and nobody criticized him. There was lots of support for the wars in the Middle East, and patriotic attitudes were everywhere.
Most liberal would be 2020. Scratch that, 2020 was actually TOO liberal. You couldn’t go ANYWHERE without hearing something about racism. Even big companies were saying Black Lives Matter and that racism was bad. BlackOutTuesday was supported by many major celebrities. Yes I know Trump and QAnon were things this year, but the backlash against Trump had boiled over to the point where he lost the election that year.

either 2002 or 2003. The years right after 9/11 where people in america was overly patriotic and islamophobic.

For liberal, I dont think it's any year after 2016. Conservatism regained so much power in 2016 with trump and brexit and it has only grown since. Liberalism was basically universal back in the early - mid 10s nowadays it's more of a 50/50 split between libs and reactionaries. 

Here in the US 2020 was undeniably liberal though in every way. Maybe in other countries less so.

YES 🙌
Being too liberal or too conservative is a bad thing. Too liberal, and you get riots, crime, preachiness, and political correctness. Too conservative, and you get jingoistic patriotism, bigoted attitudes, and closed-mindedness.
At the same time, it should also be an era where the two can at least somewhat get along. You could argue the late 2010s was balanced because there was a presence of both conservatives and liberals in the culture but the fact both made each other look like the devil coupled with BOTH becoming more extremist just made the culture of the era feel downright toxic.
IMO, I’d say the late 2000s are still the most balanced era we’ve had politically, at least in the 21st century. Obama took over in that era, but the culture hadn’t become overly preachy and politically correct like in the early or especially mid 2010s. It was also lacking in the overly patriotic attitudes the early 2000s had. Mid 2000s was a more conservative era but culturally I’d argue more balanced vs the completely conservative early 2000s. You had lots of anti-Bush satire like Fahrenheit 9/11 and Team America: World Police. His approval ratings were dropping.

That's basically a seed compared to the tree that blossomed throughout the late 10s. I remember gamergate well. 2016 is really the big shift when conservatism became a mainstream viewpoint again.