Vanhaezebrouck has been quoted as saying the striker “always lets himself down” in the wake of their 5-0 defeat to Club Brugge.
Onyekuru joined Everton for £7m from Eupen in the summer but was immediately sent out on loan to fellow Belgian side Anderlecht for the campaign.
The 20-year-old has scored nine times in 25 appearances but that has not prevented him from coming under fire from his boss.
“It does not make much sense to put Onyekuru at the centre, but when he is standing there, he does not move, and he just moves to the left… he always lets himself down,” Vanhaezebrouck was quoted as saying by voetbalkrant.com.
“He does score now and then, but the last few weeks have not been as good either, his contribution went down,” he added.
A graduate of the Aspire Academy in Qatar, Onyekuru, who has been capped twice by Nigeria, has not yet qualified for a work permit to play in the UK.