Anxiety

Hi, my daughter is 20 months old and for the last 3 months roughly she seems to have developed some kind of social anxiety.
She’s struggling with me talking to most adults apart from her dad or key workers at nursery. She’s even struggling with my family and the mums we’ve been seeing since she was a newborn. One thing that she seems to have struggled with for longer than that is adults laughing together. If I’m having a giggle with her she’s fine, but if I’m having a conversation with someone and we start to laugh she bursts out crying and there’s no calming her down.
Please let me know if you’ve been through this with your children and if you have any advice. I’ve been in touch with the health visitor who I’m due to update this month with how she’s been. I guess I just have concerns about whether this is something I should worry about of if it’s just a phase. Many thanks x