Error trying to build project because of Spotless

Reproduce the failure with ./gradlew build and ./gradlew spotlessApply at tag 5.09.54.184, then inspect the configuration-cache report and rerun with --stacktrace. The report centers on task :spotlessJava and a failed P2 dependency provision; done means identifying the cause and confirming the affected build commands complete successfully.

I am not a Java developer, I'm sorry if this is the wrong place to report a potential issue.

Thing I'm building: https://github.com/GTNewHorizons/GT5-Unofficial at tag 5.09.54.184

Running a clean ./gradlew build

./gradlew build                                                                                                                   6s  Tue 29 Sep 2026 18:06:41 BST
Calculating task graph as no cached configuration is available for tasks: build

> Configure project :
You might want to check out './gradlew :faq' if your build fails.
Build script update from 2.0.29 to 2.0.32 available! Run ./gradlew updateBuildScript
Recommend replacing '4.19.0' with '4.19' for Eclipse JDT
'indentWithSpaces' is deprecated, use 'leadingTabsToSpaces' in your gradle build script instead.
'indentWithSpaces' is deprecated, use 'leadingTabsToSpaces' in your gradle build script instead.

1 problem was found storing the configuration cache.
- Task `:spotlessJava` of type `com.diffplug.gradle.spotless.SpotlessTaskImpl`: error writing value of type 'com.diffplug.spotless.ConfigurationCacheHackList'

See the complete report at file:///new2/git/gtnh-gt5u/build/reports/configuration-cache/1n7e5fcbspgs3op8bkqx6kh2d/dl99i0g8cp9r4jwwag6nchp51/configuration-cache-report.html

[Incubating] Problems report is available at: file:///new2/git/gtnh-gt5u/build/reports/problems/problems-report.html

FAILURE: Build failed with an exception.

* What went wrong:
Configuration cache state could not be cached: field `steps` of `com.diffplug.spotless.generic.FenceStep$RoundtripAndEqualityState` bean found in field `equalityStateInternal` of `com.diffplug.spotless.FormatterStepSerializationRoundtrip` bean found in field `cleaned` of `com.diffplug.spotless.FormatterStepSerializationRoundtrip$HackClone` bean found in `com.diffplug.spotless.ConfigurationCacheHackList` bean found in field `stepsInternalEquality` of task `:spotlessJava` of type `com.diffplug.gradle.spotless.SpotlessTaskImpl`: error writing value of type 'com.diffplug.spotless.ConfigurationCacheHackList'
> java.io.IOException: Failed to provision P2 dependencies

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights from a Build Scan (powered by Develocity).
> Get more help at https://help.gradle.org.

BUILD FAILED in 31s
Configuration cache entry discarded due to serialization error.

Running ./gradlew spotlessApply

./gradlew spotlessApply                                                                                                        31.4s  Tue 29 Sep 2026 18:12:51 BST
Calculating task graph as no cached configuration is available for tasks: spotlessApply

> Configure project :
You might want to check out './gradlew :faq' if your build fails.
Build script update from 2.0.29 to 2.0.32 available! Run ./gradlew updateBuildScript
Recommend replacing '4.19.0' with '4.19' for Eclipse JDT
'indentWithSpaces' is deprecated, use 'leadingTabsToSpaces' in your gradle build script instead.
'indentWithSpaces' is deprecated, use 'leadingTabsToSpaces' in your gradle build script instead.

1 problem was found storing the configuration cache.
- Task `:spotlessJava` of type `com.diffplug.gradle.spotless.SpotlessTaskImpl`: error writing value of type 'com.diffplug.spotless.ConfigurationCacheHackList'

See the complete report at file:///new2/git/gtnh-gt5u/build/reports/configuration-cache/f5870wp0c1qsv4sz3z0jw24w1/wcpch6scbxef2wy2kiothdee/configuration-cache-report.html

[Incubating] Problems report is available at: file:///new2/git/gtnh-gt5u/build/reports/problems/problems-report.html

FAILURE: Build failed with an exception.

* What went wrong:
Configuration cache state could not be cached: field `steps` of `com.diffplug.spotless.generic.FenceStep$RoundtripAndEqualityState` bean found in field `equalityStateInternal` of `com.diffplug.spotless.FormatterStepSerializationRoundtrip` bean found in field `cleaned` of `com.diffplug.spotless.FormatterStepSerializationRoundtrip$HackClone` bean found in `com.diffplug.spotless.ConfigurationCacheHackList` bean found in field `stepsInternalEquality` of task `:spotlessJava` of type `com.diffplug.gradle.spotless.SpotlessTaskImpl`: error writing value of type 'com.diffplug.spotless.ConfigurationCacheHackList'
> java.io.IOException: Failed to provision P2 dependencies

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights from a Build Scan (powered by Develocity).
> Get more help at https://help.gradle.org.

BUILD FAILED in 5s
Configuration cache entry discarded due to serialization error.

Something about a serialization error, but I don't have a clue where to start. My disk is not full. Running Archlinux with temurin java 25, with the JAVA_HOME directory set. This same error occurs on java 26, and if I do not checkout that specific tag in the repo.