The blood-clot problem seems to be isolated to the AZ and J&J vaccines, not the Pfizer and Moderna vaccines.
https://www.ft.com/content/f76eb802-ec05-4461-9956-b250115d0577
There have been reports for both Pfizer’s and Moderna’s as well.
No they are reported for the j&j and az vaccines. it is not that they are not occurring with the pfizer and moderna vaccines, they are under reported.