Nearly 19k Pennsylvania voters have left the GOP since the Capitol attack

[TiltsAreUnderrated]

Party registration is a lagging indicator so I treat it with a grain of salt. In the case of the Capitol attack, even more so: the lion's share of the spike could plausibly be accounted for by disgusted Romney-Clinton-Biden voters feeling compelled to do something political after the Capitol attack

[TiltsAreUnderrated]

November 2016 and May 2017 registration numbers from Pennsylvania:

http://ballot-access.org/2017/05/18/new-pennsylvania-registration-data/

The Pennsylvania Department of State has released a voter registration tally for the May 2017 primary, which was held earlier this week. The percentages are: Democratic 47.94%; Republican 38.29%; Libertarian .55%; Green .15%; other and independent 13.08%.

In November 2016, the percentages were: Democratic 48.34%; Republican 37.85%; Libertarian .56%; Green .16%; other and independent 13.09%. Thanks to Michael for the link.

So here's the change from November 2016 - month of Trump's election - to February 2021:

Democrats down 2.09%
Republicans up 1.39%
Libertarians down 0.04%
Greens down 0.04%
Independent/Miscellaneous up 0.78%

Did the Inquirer or Billy Penn ever report this?

The continuation of a trend at a similar rate is not very newsworthy and there has been plenty of coverage on the gradual realignment. Take this, for instance:

https://twitter.com/MeetThePress/status/1363501395299758089
A spike in the opposite direction looks like a bigger disruption and makes for more clicks, although I personally believe it's less likely to represent a long-term shift in political sentiment.

I suppose this is akin to a recession getting more news coverage than a slower continuation of a long-term upward trend in GDP.