I (30M) got excluded from my friend group. What can I do to find out what they think of me?

TLDR; Excluded by friends, wanting to know what they think of me.

I have been participating in a social activity for 2 years now and have made some friends that I consider quite close to me as we have been seeing one another regularly. I recently found out that they have a chat group for organizing/planning other activities, and regularly hang out with one another.

My main goal for joining said social activity in the first place was to make new friends, and I have always tried my best to be polite, friendly and supportive. I initiate chats whenever I meet them and can confidently say I know almost all of the regulars there. It crushes me to know that they did not think I was close/important enough to be invited to other activities. So my dilemma now is, how do I find out what they truly think of me so that I can decide whether to stay or leave?

Any advice is very much appreciated. Thank you!