If everything is the same — same spool, same G-code, same printer — and the print suddenly starts failing or shows weak layer bonding, this is what I would try to troubleshoot the issue:
1. Dry the filament – Even if it’s the same spool that previously worked, ambient humidity can still affect it over time. A thorough drying cycle can often restore print quality.
2. Check for a partially clogged nozzle – These can be deceptive. The first layers may look fine, but a restriction builds up and causes under-extrusion later on. I would either run a cold pull or just swap to a clean nozzle to rule it out.
Those two steps solve most unexpected extrusion issues for me.