That's all possible, not proveable, but it's been done for 20 years or more so I fail to see why they wouldn't still do it. With your VPN the IP that gets sold to LiveRamp is a proxy used by many of that VPN's users. So what LiveRamp sees is your screen name Bikkuri, the timestamp when you sent that reply, and the VPN proxy addreses fetching the images that are needed to display the page. Instead of imgflip, for this page, you have bagster's imgur images.
I haven't looked at imgur until now, but it seems more privacy focused than imgflip. Here's imgur's policy https://imgur.com/privacy. They will not invade bagster's privacy very much. But what about ours? Doesn't really say. Also one more thing about VPN use. The VPN will send a proxy IP address to imgur or imgflip. But if there aren't a lot of users at that time, they will still know that some VPN user with the user name Bikkuri sent a reply to me. If they collect enough of those they will create a profile for Bikkuri based on the pages where you post and likely also the pages you visit (again depends on how many people are using that particular VPN proxy at the same time you use it). They won't have your IP, but they may have a profile without it. It will be based on posting timing and probabilistic..
I'm not up on all the tech, and VPNs probably do a better job masking you from this sort of spying than I am describing but you are quite right, probably only a paid VPN from a quality company interested in privacy, not money.
Finally I would point out that images are fun. There's no reason to be so afraid of tracking to not want them. For many years I posted here almost exclusively through a text-only VPN with no image fetching at all, never mind connected to my IP. So I saw only walls of text including text indicating there's supposed to be an image here or there. Obviously no image fetching, so no tracking. Eventually after missing out on countless funny images I bagged that idea. Now I am bagster's bitch for what it's worth.
"Now I am bagster's bitch for what it's worth."