TS yes. Absolutely normal.
You leave your late teens and early 20's which will likely be the most social years of your life, with relatively low responsibilities, and move in to mid and late 20's where many are starting their first 'career' job and/or starting a family and they need to prioritize those things, while maybe you do not yet and thus you notice their absence.
I was lucky to be in a career path (tech) in my mid 20's to early 30's in a cosmopolitan city, and we attracted similar aged people who all made great money, were mostly single and needed new friends for social outlets in the new town (to most of us) we worked in. So those years for me where not just a continuation of the University type (early 20's) socialization but an expansion on that.
But for most others they will see massive shrink in their ability to socialize as part of a group and you need to really focus on that if you want that still. Your bjj club should provide a bit of that but i bet most their treat bjj as simply their new exercise like going to the YMCA to work out and then back to the family. But join other 'interest' clubs such as hiking, kayaking, cycling, poker, chess, etc you can find, if that is what you want.
Check out the MeetUp App and see if there are active groups in your areas. When my job had me jumping cities for extended stays i used MeetUp all the time, as the usual people on it are transplants from other areas of the country or outside the country, who are looking for new social groups to mix with. My main thing was going on Comedy NIght outings with Meetup groups, and the drinks before or after. I also would do hiking, cycling and other such Meetup outings.
