The TAM (Texas A&M) and NuMex Primavera (New Mexico State U) varieties were selected/hybridized to be milder for consistency for mass food production - eg use by companies like Old El Paso.
When you buy supermarket Jalapeños you aren’t getting to choose the variety (be grateful you’re at least being told that - in the UK they’re just sold as ‘green chilies’ which could be anything) - so depending on the supplier, and whether they are offloading leftovers from a Taco Bell order, it’s going to be pot luck what you get.
It’s not a new thing - TAM peppers date back to the 1980s. Possibly changes in the supply chains during the pandemic are causing more of the milder varieties to end up in supermarkets than before?
I eat a lot of chillies - from milder Serrano up to the superhots like bhut jalokia. Jalapenos, in my experience, seem to have the biggest variance in capsaicin per specimen. Sometimes you'll get one that tastes basically like a bell pepper, and sometimes you'll get one that surprises you. Colour doesn't seem to have that much of an impact either. Could be you just got a duff pepper
What have they done? Bred all the spice out of all hot peppers ?