Thank you for responding so quickly.
I knew indexing was on commit but I wrongly assumed that a flush would provoke said commit.
I will keep the global @Transactional annotation since I like the default rollback by Spring for all the tests who don’t rely on indexes.
Since the data’s creation and the search are already executed in their own separate transactions I just need to remove the one on the test method (added by the global annotation) with @Transactional(TxType.NEVER).
And as mentionned here adding on the test method @DirtiesContext(methodMode = MethodMode.AFTER_METHOD) also renew the test context emptying datas and indexes for the next tests.