![screenshot of the examine management tab1

I migrated pages from an old site to Umbraco 13 some time ago, and since then, Examine indexing has been erratic—sometimes recognizing only 1k documents, other times none, despite having over 5k documents and 49k media files (29k of which are unused). Publishing pages has become problematic, often taking over 3 minutes or failing until a page refresh. Additionally, running a rebuild throws exceptions. Recently, attempting further programmatic page migrations results in errors.

Newtonsoft.Json.JsonReaderException: Invalid JavaScript property identifier character: @. Path '', line 1, position 8. at Newtonsoft.Json.JsonTextReader.ReadUnquotedPropertyReportIfDone(Char currentChar, Int32 initialPosition)

at Newtonsoft.Json.JsonTextReader.ParseUnquotedProperty() at Newtonsoft.Json.JsonTextReader.ParseProperty() at Newtonsoft.Json.JsonTextReader.ParseObject() at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue) at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent) at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType) at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings) at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings) at Umbraco.Cms.Core.PropertyEditors.JsonPropertyIndexValueFactoryBase1.GetIndexValues(IProperty property, String culture, String segment, Boolean published, IEnumerable1 availableCultures, IDictionary2 contentTypeDictionary) at Umbraco.Cms.Core.PropertyEditors.JsonPropertyIndexValueFactoryBase1.GetIndexValues(IProperty property, String culture, String segment, Boolean published, IEnumerable1 availableCultures) at Umbraco.Cms.Core.PropertyEditors.NestedPropertyIndexValueFactoryBase2.GetNestedResults(String keyPrefix, String culture, String segment, Boolean published, IDictionary2 propertyTypeDictionary, TItem nestedContentRowValue, IEnumerable1 availableCultures)+MoveNext() at System.Collections.Generic.List1.AddRange(IEnumerable1 collection) at Umbraco.Cms.Core.PropertyEditors.NestedPropertyIndexValueFactoryBase2.Handle(TSerialized deserializedPropertyValue, IProperty property, String culture, String segment, Boolean published, IEnumerable1 availableCultures, IDictionary2 contentTypeDictionary) at Umbraco.Cms.Core.PropertyEditors.JsonPropertyIndexValueFactoryBase1.GetIndexValues(IProperty property, String culture, String segment, Boolean published, IEnumerable1 availableCultures, IDictionary2 contentTypeDictionary) at Umbraco.Cms.Infrastructure.Examine.BaseValueSetBuilder1.AddPropertyValue(IProperty property, String culture, String segment, IDictionary2 values, IEnumerable1 availableCultures, IDictionary2 contentTypeDictionary) at Umbraco.Cms.Infrastructure.Examine.ContentValueSetBuilder.GetValueSetsEnumerable(IContent[] content, Dictionary2 creatorIds, Dictionary2 writerIds)+MoveNext() at System.Collections.Generic.LargeArrayBuilder1.AddRange(IEnumerable1 items) at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable1 source) at Umbraco.Cms.Infrastructure.Examine.ContentIndexPopulator.IndexPublishedContent(Int32 contentParentId, Int32 pageIndex, Int32 pageSize, IReadOnlyList1 indexes) at Umbraco.Cms.Infrastructure.Examine.ContentIndexPopulator.PopulateIndexes(IReadOnlyList`1 indexes) at Umbraco.Cms.Infrastructure.Examine.IndexPopulator.Populate(IIndex[] indexes) at columbusumbracocms.MyExamineIndexRebuilder.RebuildIndexes(Boolean onlyEmptyIndexes, TimeSpan delay, CancellationToken cancellationToken) in /home/runner/work/col-umbraco-cms/col-umbraco-cms/helpers/ExamineReplacer.cs:line 218