Unable to verify rsassaPss(?) signature in TimeStamp Response: "signature not created by certificate"

[kralo]

while trying to verify a signed timestamp, I found out openssl does not support it, and tried with Bouncycastle.

The data file is attached

exampleresp.zip

# build
javac -cp bcpkix-jdk18on-1.83.jar:bcprov-jdk18on-1.83.jar:bcutil-jdk18on-1.83.jar TS.java

# exec 
echo "security.provider.9=org.bouncycastle.jce.provider.BouncyCastleProvider" >> myjava.security
java -cp bcpkix-jdk18on-1.83.jar:bcprov-jdk18on-1.83.jar:bcutil-jdk18on-1.83.jar:./ -Djava.security.properties=myjava.security TS

However, it returns an error:

TimeStamp verified.
Generation time Sat Jan 24 18:09:13 CET 2026
Signer ID serial 27...
isValid?false
Exception!:
signature not created by certificate.

(source is attached TS.java.txt )