2018 Prius - Rear bumper cover removal - unknown fastener in wheel well! Please help!

Hi everyone,
I would like to first mention that I have searched online everywhere that I know if, and have never seen this fastener in any other model after going through hours of videos online.
I am trying to remove the rear bumper cover of my 2018 Prius Two Eco, to diagnose the source of a leaking trunk. So far I have only found one video of a 2016 Prius rear bumper cover removal and in that it was a normal screw and hence straight forward.

So, I was able to remove all the other fasteners around the rear bumper cover except for these 2 unique fasteners in each of the rear wheel wells. There is no obvious way to pry them out without breaking something. It appears to be holding the inner wheel well to the side bumper cover.
Any input would really be appreciated as I really want to solve the leaking trunk as soon as I can and this has me stumped!

I am unable to upload reference pictures or provide URLS to the pictures .
To use words to describe it would be hard, the best description would be it looks like a black plastic nipple that is fastened tight to the inner rear edge of the wheel well.

Will share pictures when I get allowed to add pics.

 

I'm not allowed to even post a link (never mind if its a picture or not) . Guess i'll spend time posting in other threads and just wait until i'm allowed to add pictures ‍:facepalm:.
Should have created an account a long time ago, since I've been using this site for a few months already . Learnt my lesson.

BTW the error i get when adding a link:

The following error occurred:
Sorry, you were not able to save since the content contained a link

For this Forum, before you can create content with links, you must first meet the minimum requirements

Minimum Requirements
The number of posts you have created must exceed: 4 (Yours: 1)
The number of days you have been registered must exceed: 1 (Yours: 0)

 

Wonder if I can post links now:












Yay I can!

Hope someone is able to recognize and share ideas on how to remove them without breaking anything..

 

Bump.. any inputs anyone?

 

Unfortunately there isnt a slot in the cap. The cap has a small "nipple" in the middle. Hope fully the new close ups show this better.
I didnt realize the pictures were not full size. Apologies, here are a few more close ups and I hope these are clearer.






From the Inside of the wheel well.



BTW all the marks/deformations on it are by me trying to pull/wedge it out(didnt seem to have space to wedge it) with a flat-head screwdriver.

 

Okay. Will give it a shot today and update. Fingers crossed if that is it.

 

You were correct, pressing down did work, although I still ended up breaking it while prying because it wouldn't come out much. (Pushing it in only made it a bit more loose). Thank you so much!!

Seems it was holding the bumper cover with the plastic frame that the bumper cover is latched on to. Not too worried about it since there were 4 other latches on that plastic frame to which the bumper cover holds on to.
Might use a zip tie for the sake of it at the end.


So found that water is leaking in through the plastic screw hole used to screw in the bumper cover. Need to find out how to take care of that now. Anyway progress is progress

 

I agree with all that you mentioned. I had the exact same question i.e is it even OEM. Anyway I ended up popping the top off when trying to remove it (after i was able to push the middle in about 1 cm). I checked online for what is used normally over there in toyota's website(Part number: 90467-05170) and picked it up for both the rear wheel wells. Will try them tomorrow and see if it fits. For now the bumper is holding on fine (took it for a decent distance drive and didnt notice anything).

Oh and fixed the leaking trunk problem too. Turned out to be due to a worn out Screw Grommet(Part Number: 90189-06242) that holds the rear bumper with a screw.
New Vs Old pics below: (Notice the much thicker black ring)



Spot on the car it was leaking: