lMotherboard Manual:
https://gzhls.at/blob/ldb/f/2/e/5/48ffc54e4a3d0a923918dc8cb0da6c3c8c1d.pdf
Per Pages 1-2 and 1-3 the connector ( #9) is indeed a USB 3.2 Generation connector.
(Do verify that I did find the applicable motherboard manual.)
And as stated in your original post the blue portion of the 20 pin plug is indeed stuck/remains in the socket.
To remove the blue plug what I would do is use as small a pair of pliers as possible to grasp the blue connector lengthwise and gently try to rock it, again lengthwise) up and out.
That is what I would try for starters. If unsuccessful I would maybe try pulling up and out switching from end to end while gripping across the narrow width... Again alternating small tugs on each end.
Failing that I would probably try to further my creativity along the same lines.
Key is to be gentle and very very careful.
But do wait for other comments and suggestions. There may be other ideas and suggestions - I have no problems with that.