It doesn't really mean anything, but if you're curious:
When I was younger, I used to watch a brazillian youtuber (I'm brazillian incase you didn't know). This youtuber's name is Godenot, and in some games he played his fans would sometimes add "[GD]" before or after their username so he'd recognize them as fans if he saw them while recording.
One of the games he played a lot was Roblox, so when I decided to make my own Roblox account, I decided to reference this and named my account... "GDhi". I got really into Roblox during this period, but one day while playing a game, a hacker joined and began screwing everything up and then banned everyone in that server from that Roblox game.
Since I really liked that game, I decided to make an alt so I could keep playing. I didn't have any new name ideas for the alt, so I decided to swap the two halves of that username, but added the 3 at the end since "HIgd" was already taken.
Over time I played more and more on this alt until it ended up becoming my main Roblox account. I met a lot of friends there, and when I finally made my Discord account in 2019 I decided to keep the name. After that point, the name just stuck