Hey River,
Hard for me to understand the magnitude of this shift based on macro factors,

Agreed. The Covid crash was the steepest and fastest drop combined in market history. These signals all flipped negative reasonably quickly (inside of 4 weeks IIRC) so that, if followed, you were out of the market without catastrophic damage. Then the shorter term and breadth signals flipped to bullish. With pitchforks out and a loud noise of government intervention in March & April, and a pinch of cynicism about dependence on QE, it was worth taking a flyer on a 25% stock position in April... which then turned into a 75% allocation by June as "the market" clearly voted to buy up the entire big cap tech and internet sectors with all that helicopter money.
THAT was hard to understand.

What these and similar indicators do is give a sense of the big money flow - the actual dollars - going into and out of equities. Regardless of the daily punditry static on "macro".

specific preferred's worth looking in to?

I try to pick them mechanically based on at least one of Moodys or S&P giving them an investment grade, then 4-5% yield above Treasuries. As preferred prices crashed last year along with bonds, it was super easy to find high quality preferreds at prices 20 to 25% below par (making the yield from purchase worthwhile). Didn't touch them until the bond market started to bottom. Then picked up some good bargains - (and realty equity like O) - GLP-A, CSSEN, ATH-C,CADE-A, MS-E, OPINL examples.
Fidelity's screener is decent. But for real details, two free resources I'm aware of -
quantumonline.com: QuantumOnline.com - Preferred Stocks, Common Stocks, Exchange Trade Securities (ETFs) and Convertible Securities Information
Google: Reits and Preferred Stocks

There's always the PGX or PFF (higher fee) ETFs, but that's like owning a bond fund - and at a 5%+ yield the spread isn't close to enough to compensate for the downside risk over Treasuries when you can get 4 1/4 from a govt money fund.