A big office complex in Sunnyvale has staggered into a default on its loan, a financial setback that suggests post-coronavirus maladies still afflict the commercial real estate market in the Bay Area.

According to commercial real estate brokerage CBRE, office leasing activity had been up 23% year over year in the last months of 2024. But fears about the economy could impact companies’ plans.

In the Boston region, for example, owners of at least 10 life-sciences locations are now offering those buildings for office space instead of lab space, according to brokers and other real-estate ...