Yes, Democrats underperformed in the suburbs, which is basically what happened nationwide. For example, Trump won El Paso County (Colorado Springs) by 11%, Gardner won it by 16%, and Doug Lamborn (the Republican incumbent in CO-05) won it by 19%. Likewise, Jason Crow did two points worse than Biden in CO-06 (Denver suburbs). Biden, Hickenlooper, and Mitsch Bush all won Pueblo County, yet the latter two did a tad worse than the former.
Here's the results by congressional district:
CO-01 (City of Denver): Biden +53.5, DeGette +50
CO-02 (Boulder + Fort Collins): Biden +30, Neguse +26
CO-03: (Western Slope + Grand Junction + Pueblo + ski towns like Aspen): Trump +5.5, Boebert +6
CO-04 (Eastern Plains): Trump +16, Buck +23.5
CO-05 (Colorado Springs): Trump +13, Lamborn +20
CO-06 (Aurora): Biden +19, Crow +17
CO-07 (West Denver suburbs): Biden +23, Perlmutter +21.5
https://www.dailykos.com/stories/2020/11/19/1163009/-Daily-Kos-Elections-presidential-results-by-congressional-district-for-2020-2016-and-2012
It's worth noting that it's not just suburban ancestrally R Biden voters splitting their tickets, though. Ken Buck performed significantly better than Trump in his rural district.
Ken Bucks district is not really rural. 80% of the district lives in Douglas or Weld. Its more exurban/suburban with a few people who live in the plains portion.
