My best guess would be that you have some petg left in the nozzle that for whatever reason isn’t being melted and pushed out, what you could try is doing a cold pull
If you haven’t done it before, you basically heat up the hotend, feed in some plastic, then you turn off the heat and let it cool down until the plastic is partially hardened, then you yank on the filament
If everything goes right, the plastic down in the nozzle will be yanked out, and pull with it any impurities, leaving the nozzle clean and unclogged
Alternatively buy a new nozzle that you only use for PLA, i have heard a lot of people having issues like this when switching back and forth with the same nozzle
My best guess would be that you have some petg left in the nozzle that for whatever reason isn’t being melted and pushed out, what you could try is doing a cold pull
If you haven’t done it before, you basically heat up the hotend, feed in some plastic, then you turn off the heat and let it cool down until the plastic is partially hardened, then you yank on the filament
If everything goes right, the plastic down in the nozzle will be yanked out, and pull with it any impurities, leaving the nozzle clean and unclogged
Alternatively buy a new nozzle that you only use for PLA, i have heard a lot of people having issues like this when switching back and forth with the same nozzle