When add a warning log at GetCharsetInfoByID(link), it will be flooded by logs. From the log, we could get the collation ID is 0, seems it not be set in TiDB (not sure about it, just guess).

The error log is below,
[2021/11/11 16:19:47.624 +08:00] [ERROR] [cop_handler.go:453] ["Unable to get collation name from ID, use default collation instead."] [ID=0] [stack="github.com/pingcap/tidb/store/mockstore/unistore/cophandler.fieldTypeFromPBColumn\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/cop_handler.go:456\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.(*evalContext).setColumnInfo\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/cop_handler.go:205\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.newClosureExecutor\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/closure_exec.go:248\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.buildClosureExecutor\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/closure_exec.go:170\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.handleCopDAGRequest\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/cop_handler.go:118\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.HandleCopRequestWithMPPCtx\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/cop_handler.go:71\ngithub.com/pingcap/tidb/store/mockstore/unistore/cophandler.HandleCopRequest\n\t/Users/jasonmo/tidb/store/mockstore/unistore/cophandler/cop_handler.go:59\ngithub.com/pingcap/tidb/store/mockstore/unistore/tikv.(*Server).Coprocessor\n\t/Users/jasonmo/tidb/store/mockstore/unistore/tikv/server.go:565\ngithub.com/pingcap/tidb/store/mockstore/unistore.(*RPCClient).SendRequest\n\t/Users/jasonmo/tidb/store/mockstore/unistore/rpc.go:236\ngithub.com/pingcap/tidb/store/mockstore.(*clientRedirector).SendRequest\n\t/Users/jasonmo/tidb/store/mockstore/redirector.go:61\ngithub.com/tikv/client-go/v2/internal/client.reqCollapse.SendRequest\n\t/Users/jasonmo/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.0-alpha.0.20211103022933-5ae005dac331/internal/client/client_collapse.go:74\ngithub.com/tikv/client-go/v2/internal/locate.(*RegionRequestSender).sendReqToRegion\n\t/Users/jasonmo/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.0-alpha.0.20211103022933-5ae005dac331/internal/locate/region_request.go:1128\ngithub.com/tikv/client-go/v2/internal/locate.(*RegionRequestSender).SendReqCtx\n\t/Users/jasonmo/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.0-alpha.0.20211103022933-5ae005dac331/internal/locate/region_request.go:980\ngithub.com/tikv/client-go/v2/txnkv/txnsnapshot.(*ClientHelper).SendReqCtx\n\t/Users/jasonmo/go/pkg/mod/github.com/tikv/client-go/v2@v2.0.0-alpha.0.20211103022933-5ae005dac331/txnkv/txnsnapshot/client_helper.go:108\ngithub.com/pingcap/tidb/store/copr.(*copIteratorWorker).handleTaskOnce\n\t/Users/jasonmo/tidb/store/copr/coprocessor.go:731\ngithub.com/pingcap/tidb/store/copr.(*copIteratorWorker).handleTask\n\t/Users/jasonmo/tidb/store/copr/coprocessor.go:645\ngithub.com/pingcap/tidb/store/copr.(*copIteratorWorker).run\n\t/Users/jasonmo/tidb/store/copr/coprocessor.go:382"]