Hello Ulrich,
Sorry for the late response to your question. On our site you can find package information for all our chips. Package Information - Support (monolithicpower.com) For this package, if it was manufactured past 2010, then the top marking “PPPY”. “PPP” is the part code, while “Y” denotes the year. So for your MPQ4568GQ-Z, “ACVH”, the H is for 2017.
The date decoding pdf I used: top_marking_format_decoding_rule.pdf (monolithicpower.com)
Thank you,
Vinh Tran