I've never bothered looking too hard before, but have noticed my WC pan
connector (push fit 110 at the non WC end) had some quite pronounced
mould seam ridges down both sides.

On this I've carefully pared them off with a stanley blade, leaving a
slight groove (original defect, not knife related).

Happened to notice even the Floplast Tee 110 I have also has slight (but
not as pronounced) mould seam ridges.

Do people normally pare or sand these off?

I've not had any leaks before, but then my joints face the right way and
are never under pressure and I don't have the kit to pressure test my
system.

So this is just a curiosity "learning to do things better" kinda muse...