Not necessarily.
Have you had a positive HPT? If you haven’t had a positive test then it’s just a clot. From my 30’s onwards all my periods were like that tbh.
It could just be a larger clump of lining, some women (myself included) have decidual casts where the lining comes out all in one piece, so it could be a partial bit, rather than an actual decidual cast. sometimes it’s just one of those things, unfortunately, but generally nothing to worry about. If it starts happening regularly do speak to the dr.
If you have had a positive test, then I’d say it doesn’t look like good news I’m afraid.