Underextrusion help

I have a CR10 & Ender 3 with stock parts except for bowden tube, nozzle, glass bed and they’re both having the same issues.

My Ender 3 was the first to go with the underextrusion. Pulled filament and no evidence of there being a gap between bowden & nozzle. I do not claim to be an expert but it doesn’t look like anything at all what you see on the sub when there’s clear sign of a gap. Took apart bowden tube and noticed there’s some plastic gunk that must be blocking the flow. I’ve never taken apart a bowden tube for the heck of it when there isn’t a clear sign of blockage so I don’t know if the gunk in there is normal or not and a sign of what the issue is.

Replaced bowden, nozzle and same issue so now I’m thinking that I’m doing something wrong. Maybe there is a gap & I’m an idiot. Still, I know in the past that even if I replace the nozzle & bowden that I’d at least get a good few minutes of picture perfect first few layers but I did not get that. So my conclusion at the time was maybe the filament is bad. Replaced filament, things are awesome, high five myself but 20 minutes later the exact same issue!! Everything was the same before I replaced the tube & nozzle. At this point I just went to sleep.

Next day my CR10 now has the exact same issue as Ender 3. I performed the same steps and it’s the same thing all over again. It’s just so odd that both printers would all of a sudden have the same issue. It’s just a coincidence that both are failing at the same time? Perhaps it’s something in Cura?

At this point I’m stuck. I would appreciate any ideas.