I don't want to be the guy to say "downtown has always sucked," but in the dozen years I've lived here (a dominant portion of which I've worked downtown and participated in comedy took me downtown often), downtown has never been all that great. It's where people go to work, then they leave, and then the bridge and tunnel folks come to visit the skeezy clubs that shut down the alphabet district Friday and Saturday nights. I've always found it claustrophobic and dirty, and while Portland is a more houseless-friendly city than others it's more tolerant/look-the-other-way than assistive, and downtown has always been the safe space in the city's "I don't care what happens as long as I don't have to look at it from my house/apartment window" approach.
So of course the pandemic has hit downtown really hard; with businesses going remote and bars/restaurants closing down or pivoting their business models, there's little reason to be down there. I do think a lot of businesses boarded their windows preemptively, which can lend an air of destitution and disarray, even if the windows behind them are clean and intact; this has especially been the case for corporate entities (I recall seeing a boarded-up Target near the airport, where nobody is protesting/acting out). And I think the lack of upkeep is partially a financial issue as well as part of PPD's penchant for looking the other way ever since they heard people cry "defund the police."
I will say I have spent more time downtown over the last few months, hitting up the farmer's market, the art museum, and my office in slabtown, and there are more people out and fewer shuttered windows. It can get my hackles up to hear people complain about the state of the city, because there's a lot of nuance to why things are as they are, yet to speak to friends/family out of state, heck even coworkers in Tigard, our downtown was a complete war zone during summer '20 and it's "such a shame."