Are you talking about keystore currently present on expo server or the one you want to upload? What about the other one?
This keystore is in pkcs format (.p12 file) it’s just named incorrectly. To convert it back to jks follow those instructions build:android failed in task :app:packageRelease (attempting to build 64-bit bundle using new keys generated by `expo opt-in-google-play-signing` process) - #8 by wkozyra
EDIT: fixed wrong link, thanks @vna