Since upgrading from v12.3.6 to v13.1.0 we are getting a new error occasionally in the logs:

Lucene.Net.QueryParsers.Classic.ParseException: Cannot parse '(id: OR __Path:\-1*,,*)': Encountered " <OR> "OR "" at line 1, column 5.
Was expecting one of:
    <BAREOPER> ...
    "(" ...
    "*" ...
    <QUOTED> ...
    <TERM> ...
    <PREFIXTERM> ...
    <WILDTERM> ...
    <REGEXPTERM> ...
    "[" ...
    "{" ...
    <NUMBER> ...

 ---> Lucene.Net.QueryParsers.Classic.ParseException: Encountered " <OR> "OR "" at line 1, column 5.
Was expecting one of:
    <BAREOPER> ...
    "(" ...
    "*" ...
    <QUOTED> ...
    <TERM> ...
    <PREFIXTERM> ...
    <WILDTERM> ...
    <REGEXPTERM> ...
    "[" ...
    "{" ...
    <NUMBER> ...

   at Lucene.Net.QueryParsers.Classic.QueryParser.Jj_consume_token(Int32 kind)
   at Lucene.Net.QueryParsers.Classic.QueryParser.Clause(String field)
   at Lucene.Net.QueryParsers.Classic.QueryParser.Query(String field)
   at Lucene.Net.QueryParsers.Classic.QueryParser.Clause(String field)
   at Lucene.Net.QueryParsers.Classic.QueryParser.Query(String field)
   at Lucene.Net.QueryParsers.Classic.QueryParser.TopLevelQuery(String field)
   at Lucene.Net.QueryParsers.Classic.QueryParserBase.Parse(String query)
   --- End of inner exception stack trace ---
   at Lucene.Net.QueryParsers.Classic.QueryParserBase.Parse(String query)
   at Examine.Lucene.Search.LuceneSearchQueryBase.NativeQuery(String query)
   at Umbraco.Cms.Infrastructure.Examine.DeliveryApiContentIndex.PerformDeleteFromIndex(IEnumerable`1 itemIds, Action`1 onComplete)
   at Examine.BaseIndexProvider.DeleteFromIndex(IEnumerable`1 itemIds)
   at Umbraco.Cms.Infrastructure.Examine.Deferred.DeliveryApiContentIndexDeferredBase.RemoveFromIndex(IReadOnlyCollection`1 ids, IIndex index)
   at Umbraco.Cms.Infrastructure.Examine.Deferred.DeliveryApiContentIndexDeferredBase.RemoveFromIndex(IReadOnlyCollection`1 ids, IIndex index)
   at Umbraco.Cms.Infrastructure.Examine.Deferred.DeliveryApiContentIndexHandleContentChanges.<Execute>b__7_0(CancellationToken _)
   at Umbraco.Cms.Infrastructure.HostedServices.QueuedHostedService.BackgroundProcessing(CancellationToken stoppingToken)

We don't do any Lucene queries from our code, and as per the stack trace, the source of the error is the content delivery api.

I did rebuild all the lucene indexes after the upgrade. Other than these errors the site is running fine.