Lot of eventID 4999 related to ActiveSync on my Exchange Servers

Same ErrorID 4999 here, only with another processID (mostly 25636, but also others):

Watson report about to be sent for process id: 25636, with parameters: E12, c-RTL-AMD64, 15.01.2308.021, w3wp#MSExchangeSyncAppPool, MSExchange ActiveSync, Microsoft.Exchange.AirSync.Common.SchemaConverter.Entity.EntityContentProperty.get_MIMEData, UnexpectedCondition:NotImplementedException, 0, 15.01.2308.021.
ErrorReportingEnabled: True
exData=|exHResult=|exStacktrace=bei Microsoft.Exchange.AirSync.Common.SchemaConverter.Entity.EntityContentProperty.get_MIMEData()
bei Microsoft.Exchange.AirSync.Common.SchemaConverter.AirSync.AirSyncContentProperty.InternalCopyFrom(IProperty sourceProperty)
bei Microsoft.Exchange.AirSync.Common.SchemaConverter.AirSync.AirSyncContent14Property.InternalCopyFrom(IProperty sourceProperty)
bei Microsoft.Exchange.AirSync.Common.SchemaConverter.AirSync.FlexibleSchemaStrategy.ExecuteCopyProperty(IProperty srcProperty, AirSyncProperty dstAirSyncProperty)
bei Microsoft.Exchange.AirSync.Common.SchemaConverter.AirSync.AirSyncDataObject.CopyFrom(IProperty srcRootProperty)
bei Microsoft.Exchange.AirSync.MailboxItemFetchProvider.BuildResponse(XmlNode responseNode)|exTargetSite=MSExchange ActiveSync Microsoft.Exchange.AirSync.Common.SchemaConverter.Entity.EntityContentProperty.get_MIMEData|exSource=|exMessage=|exComplete=

Everything started on 13.2.2022 with EventID 4999 but other message within:

Watson report about to be sent for process id: 16564, with parameters: E12IIS, c-RTL-AMD64, 15.01.2308.014, w3wp#MSExchangeOWAAppPool, M.E.C.Owa2.Server, M.E.C.O.S.C.OwaMapiNotificationManager.SubscribeToSuiteNotification, System.NotSupportedException, 80d2-dumptidset, 15.01.2308.014.
ErrorReportingEnabled: True

Over 160 views in this thread but no solution or at least a hint?