OK, I contacted the realtor on this site for Big Bear Lake Kmart, inquiring about leasing it:
https://leasespaces.jll.com/?propertyId=750744-lease
They wrote back to me that, sadly, the store is NOT closing. They are merely leasing 4 store spots, in that shopping center adjacent to Kmart. From that site "Anchored by Kmart
Home to Big Bear Mountain Resorts with over 6,000,000 visitors per year
Four shop spaces totaling 5,805 SF in the adjacent building next to Kmart".
Further, that store is currently hiring a store manager:
https://jobs.sears.com/en-US/job/store-manager-kmart-4047-costa-mesa-ca/J3W3565ZKQR48M63M5G