Hi Workshop crowd,
We've got a house that was built in 2003 and in the main shower it has one of those dodgy white plastic shower drains. Unfortunately, at some point it's started sinking into the ground, and gaps have appeared.
Shower drain, note the holes around the edge. May have been grouted at one point but perhaps the grout has fallen away?
There might have been grout around it at one point that's pushed away over time. It wouldn't surprise me to learn it was a bad job done when it was built, as there are other.. questionable things about the house that we've been learning over time.

As you can see above, the drain cap pops out relatively easily. I'm not sure if it's meant to do that.

I'm assuming it's meant to be concrete under the tiling, and it appears that it's been eroding away over time, likely due to the holes in the grout.

And then when you put the drain cap part back in, you can see it doesn't sit flush to the pipe.
My inclination is to silicone the heck out of it and see what happens, but I figured I best ask if anyone knows if that will cause more issues down the track.
Ideally, I'm looking for a DIY fix that only needs to last a couple of months. The bathroom needs renovating anyway, and I'd rather have it ripped out and replaced altogether along with the rest of the bathroom.
Is this something that I can just silicone and call a day for a few months until it gets junked? Or, if not silicone, is there some other DIY option that's feasible without ripping out the tiles and having it retiled?