Strange layer problems

From the included picture, what could be going on here?It's an Ender3 v2, I just did the exact same print which came out fine, but after removing the glass base to take the print off, and put it back, this happened.That's not a shadow by the way, if you see towards the right in the light, the layer has clear lines for some parts, but then it's as-if it's really flat.Could this be a dodgy filament?I levelled the base before the print, using the paper trick, and all was as it usually is before a print.I also noticed when it printed the skirt, it sometimes doesn't print at all in some areas - I can't see how it's a levelling issue since the paper trick was used in all 4 corners.Any advice or comments greatly appreciated.

Just my opinion.......

I think the nozzle is too close to the bed, try increasing the 'Z' offset in +0.02mm increments and print one of the many bed leveling STL files on such as Prusa Printables.

Always a good idea to calibrate the 'e' steps for the extruder.

Loads of videos on Youtube about bed leveling and calibrating.

I think it's Skirt Issue. If the skirt isn't printing consistently, it could indicate an issue with the initial layer adhesion or bed leveling. Ensure that the nozzle is close enough to the bed for proper adhesion but not too close to cause issues with filament flow.