I tried:
implementation fg.deobf("curse.maven:timeless-and-classics-zero-1028108:6632240-sources-6633203")
I got:
Execution failed for task ':compileJava'.

Could not resolve all files for configuration ':compileClasspath'.
Could not find curse.maven:timeless-and-classics-zero-1028108:6632240-sources-6633203_mapped_parchment_2023.08.20-1.20.1.
Required by:
project :
Could not find net.minecraftforge:forge:1.20.1-47.4.0_mapped_parchment_2023.08.20-1.20.1.
Searched in the following locations:
- file:/C:/Users/user/.gradle/caches/forge_gradle/bundeled_repo/net/minecraftforge/forge/1.20.1-47.4.0_mapped_parchment_2023.08.20-1.20.1/forge-1.20.1-47.4.0_mapped_parchment_2023.08.20-1.20.1.pom
- file:/C:/Users/user/.gradle/caches/forge_gradle/bundeled_repo/net/minecraftforge/forge/1.20.1-47.4.0_mapped_parchment_2023.08.20-1.20.1/forge-1.20.1-47.4.0_mapped_parchment_2023.08.20-1.20.1.jar
Required by:
project :

Do I need to Implement something else?

do you sure you have placed it in the correct repositories block? There are multiple repositories blocks in the script. Because I noticed you placed curse maven next to parchment, which is often for gradle plugin but not the project itself.
could you upload the complete build.gradle file but not snippet? it's indeed like repositories not being configured correctly (or being correctly configured but requiring a proxy to connect)...

I don't know that there are multiple repository blocks. Maybe this is the issue. Please check the code if you find something

buildGradle.txt

have you add curse maven in repositories part?

I did it like the "readme" said. maybe you find an important error in my code or you have another idea.
Tanks for your help :)

`repositories {
maven {
name = "ParchmentMC"
url = "https://maven.parchmentmc.org"
}
exclusiveContent {
forRepository {
maven {
url "https://cursemaven.com"
}
}
filter {
includeGroup "curse.maven"
}
}
}

dependencies {
minecraft "net.minecraftforge:forge:1.20.1-47.4.0"

implementation fg.deobf("curse.maven:timeless-and-classics-zero-1028108:6632240-sources-6633203")

tasks.named('processResources', ProcessResources).configure {
var replaceProperties = [minecraft_version : minecraft_version, minecraft_version_range: minecraft_version_range,
forge_version : forge_version, forge_version_range: forge_version_range,
loader_version_range: loader_version_range,
mod_id : mod_id, mod_name: mod_name, mod_license: mod_license, mod_version: mod_version,
mod_authors : mod_authors, mod_description: mod_description,]

inputs.properties replaceProperties

filesMatching(['META-INF/mods.toml', 'pack.mcmeta']) {
    expand replaceProperties + [project: project]
}

}

// Example for how to get properties into the manifest for reading at runtime.
tasks.named('jar', Jar).configure {
manifest {
attributes(["Specification-Title" : mod_id,
"Specification-Vendor" : mod_authors,
"Specification-Version" : "1", // We are version 1 of ourselves
"Implementation-Title" : project.name,
"Implementation-Version" : project.jar.archiveVersion,
"Implementation-Vendor" : mod_authors,
"Implementation-Timestamp": new Date().format("yyyy-MM-dd'T'HH:mm:ssZ")])
}

// This is the preferred method to reobfuscate your jar file
finalizedBy 'reobfJar'

}`