This is a piece of concept art that was revealed to us in Half-Life Alyx Final Hours which shows a concept of Jeff with creatures that resemble the Hydra a cut enemy from Half-Life 2 designed by Ted Backman, also a Tentacle from Half-Life 1 can be seen on Jeff and in the background, the Tentacle can also be seen in many other places in Half-Life Alyx. Half-Life Alyx in many places has taken or tried to take from the Half-Life 2 Beta content, for instance one of the concepts from The Final Hours was the Cremator.
They took the cremator and the hydra from us... AGAIN
Unfortunately yeah
Oh my gosh, baby tentacles. They're adorable, I want to grow one in a little flower pot.
There's another concept of Jeff on the Wiki with even more resemblance to Hydras. Also there seem to be a few broken/unfinished particle systems that would've acted as the Infant Hydras on Jeff's back that are still in the files, oh well at least Tentacles made it into the final game.
I didn't know about the particle systems, VALVE WHY!