Hi @NWEASD
Has your problem been solved?
Is your 'OData__ModerationStatus' column a choice type?
I test on my side with the filter below and it can works well.
You can try it again with the filter below.
Created le '2021-11-16' and OData__ModerationStatus eq 'Pending'


Regarding this error, please check if there is a blank value in your EndDate column.
If yes, please review the items in the list and fill that blank field and try again.

Hope the content above may help you.
Best Regards