When did downtown start becoming abandoned?

I live pretty close to the downtown area and today I was taking a walk to drop something in the mail before it is collected tomorrow morning, and in my walk I was just looking at the closed signs or abandoned storefronts of old businesses and it made me wonder when did the downtown start closing up?

I've only been living here about a year and this area always looked like it coud be a vibrant, amazing place and did downtown just never recover post-pandemic or has it been slowly becoming abandoned over the past decade or so?