Here is the working code I have prepared. one of the important points is setUrlEncodingEnabled() and urlEncodingEnabled().
you can check following links as well
CustomAppContext
RestAssure URL Encoding
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ConfigurableApplicationContext;
public class CustomApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext>
{
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext)
    {
        System.setProperty("org.apache.tomcat.util.buf.UDecoder.ALLOW_ENCODED_SLASH", "true");
    }
}
import static io.restassured.RestAssured.given;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.when;
@ActiveProfiles("it")
@RunWith(SpringRunner.class)
@TestPropertySource(locations = "classpath:application-it.properties")
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ContextConfiguration(initializers = CustomApplicationContextInitializer.class)
public class TeamControllerIT {
    @LocalServerPort
    private int port;
    @Autowired
    private Environment environment;
    private RequestSpecification correctCredentialsPortSpecUrlEncodedForService;
    @MockBean
    private TeamService teamService;
    @Before
    public void setUp() throws Exception {
        JSONArray rolesArray = new JSONArray();
        rolesArray.put("user");
      
        String token = JWTUtil.createSelfSignedTestToken(environment.getProperty("publickey"),
                environment.getProperty("privatekey"), Date.valueOf(LocalDate.parse("2999-01-01")), "integrationTest",
                environment.getProperty("testclient"), rolesArray);
        correctCredentialsPortSpecUrlEncodedForService = new RequestSpecBuilder()
                .addHeader("Authorization", "Bearer " + token)
                .setPort(port)
                .setUrlEncodingEnabled(false)
                .build();
    }
    @Test
    public void shouldGetUsersInTeam() throws UnsupportedEncodingException {
        String teamID = "slash/slash";
        when(teamService.getTeamUsers(teamID)).thenReturn(List.of(
                User.builder().userId("user1").firstName("user").lastName("1").email("user1@test.com").build(),
                User.builder().userId("user2").firstName("user").lastName("2").email("user2@test.com").build()
        ));
        List<KeycloakUserDTO> list2 =
                given()
                        .spec(correctCredentialsPortSpecUrlEncodedForService)
                        .log().ifValidationFails()
                        .contentType("application/json")
                        .urlEncodingEnabled(false)
                        .pathParam("teamIDEncoded", urlEncodeString(teamID))
                        .when()
                        .get("/userservice/teams/{teamIDEncoded}/users")
                        .then()
                        .log().ifValidationFails()
                        .statusCode(200)
                        .and().extract().jsonPath().getList("", KeycloakUserDTO.class);
        assertThat(list2.size()==2);
    }
    private static String urlEncodeString(String value) throws UnsupportedEncodingException {
        return URLEncoder.encode(value, StandardCharsets.UTF_8.name());
    }
    private String activeProfile() {
        return environment.getActiveProfiles()[0];
    }
}