[snassar]

I don't know how it is in other countries. We recently wondered what the right thing to do is and the Citystate of Berlin has an FAQ on recycling: https://www.bsr.de/die-top-13-mullmythen-26874.php which makes some things explicit:

(It is in German, but deepl translated the relevant section)

Do empty bottles and packaging have to be washed out?

No. Because the packaging is rinsed out in the recycling process, when the sorted plastics are shredded. It is only important that all packaging is emptied of residues [ed. The translation misses tmthat they mean large residue or levtover amounts], is not stacked and the lid is removed.