Primary images keep getting changed for these titles

Half-Life (Video Game 1998) - IMDb

Half-Life 2 (Video Game 2004) - IMDb

I have uploaded and changed the primary images to these 2 titles multiple times but someone keeps deleting them and uploading lower quality images and setting them as primary posters. 

Currently my poster submission is in pending status for the second title and a low quality poster has been set as primary by this person. This is the primary image this person wants for some reason and keeps deleting any higher quality image I have uploaded so far (this has been going on for about a month). I want to request the IMDb staff to take a look at this and take steps that this behavior is not repeated.

I would've updated the link to my higher quality poster as soon as it got accepted. Please note that this person will definitely remove that poster within a couple of hours of it being posted.

I am attaching the correct images here in hopes that these would be permanently set as primary posters so that they are not tampered with. These posters are copyright free versions (posters with trademarks removed) of original posters sourced from steamgriddb and official steam poster for the game respectively.

For Half-Life (Video Game 1998) - IMDb