https://www.sjscycles.co.uk/gear-spares/shimano-duraace-st9000-name-plate-fixing-screws-right-hand-y63x98020/ says that
Y63X98020 is a name plate for the right hand lever of a ST-9000 brifter.
A review on that link says:
unfortunately I mistakenly ordered st9000 I returned for credit and ordered the correct st9001 very happy
So from that I conclude you have ST-9001 brifters, which are 30% "thinner" and therefore a subtly different shape in the hood/body.
Some googling about suggests the part number you need for a ST-9001 is
Y00G98020 but take this with caution, I'm certainly no expert.
Photo of the suggested part number - looks about right, but hard to know for sure.
Fortunately its only a $12/£12/€15 item, but then it is also a single piece of plastic.