My friend cannot break blocks

For some reason, my friend now cannot break blocks on our server. He is in survival mode. We have lots of plugins installed on our server, but this happened randomly so I don't think it is plugin-related. This happened recently before on another server, but he could still break some blocks in a couple chunks. The border wasn't on any chunk borders, it seemed quite random. I also recently linked my google drive account to the server for backups. If anybody knows what the problem is or how to fix it, please let me know.

No message. Here is a screenshot of my plugins folder. i also have Terralith world generation, amplified nether, treecapitator, and amplified end generation datapacks.