I have this PCB where circular solder points are perfect, while square ones ("negative legs") seem to have solder repellent fields around them.

Is this a known thing or my skill/material issue? If the former, how should I solder these things?

#soldering

@buherator only possible reason that comes to mind is that negative leads might be tied to a big ground plane, thus sucking away a lot of heat. Keeping the soldering iron on them a bit longer ( or a stronger soldering iron, bigger tip , but not higher temperature) might help.

@FuzzyAleks @buherator agreed, can't think of any other reason either. imo it's not a skill issue when you have trouble with these, it's just harder to solder - what Aleks said should help.