It is easy to feel broken around these kind of things, and I think for a lot of us with insecure attachment styles there are core beliefs that align with that thought (for instance, without being aware of it for a long time, I have a core would about being unlovable). Some good news is that it's possible to work on and start healing, and there are a lot of resources available to help that didn't used to exist - some good youtube channels, subreddits, therapy, etc. I've been working on my attachment style for the last couple of years and I've still got plenty of distance to go but I have noticed big positive changes in my life from the work I have been doing.

I have long had difficulty with compliments myself. I started going to therapy about two years ago and early on noticed that I had a hard time when my therapist complimented me. One thing that I noticed was that I always ran the compliment through my own filters to evaluate it. And similar to what you said, if it was something I already knew I did well it didn't really seem like a big deal to me, and if it was something that I didn't think I deserved a compliment for than I more or less just dismissed it as uninformed I guess.

After talking with a friend about it, I decided to work at trying to let the compliments in with out as much filtering, to just feel them I guess. I was doing a lot of work on other things in therapy at the same time which I imagine also were factors, but I did eventually get more comfortable with compliments to where now it is easier for me to just appreciate them and feel good without needing to analyze them so much.

I mentioned this in a nested comment as well, but I have found the /r/AvoidantAttachment subreddit to be a supportive community for people with avoidant attachment. It also has a list of resources on the sidebar for learning more about that attachment style and for learning to work with it better/more healthily. I've been working on attachment issues in therapy the last couple of years and have found it really helpful, it has made a big difference in my life.

Attached is a good read, but particularly since this is a thread relating to avoidant attachment styles, I'll mention that book is considered to be a bit harsh towards avoidant attachment styles particularly. I've found the /r/AvoidantAttachment subreddit to be a nice community for avoidants to support each other, and it has a list of resources on the side bar that can be helpful for learning more about those attachment types.