Pretty much yes, it is expected. If you really must minimize blocking:
Also make sure you never make any call that acquires a cellular mutex from the loop thread. The most common problem is Cellular,RSSI(), but any cellular call can exhibit this behavior.
Only perform publish operations from a background worker thread, not ever from the main loop thread.
Gen 3 (B Series SoM, Boron, Tracker) devices have slightly different blocking behavior than the Electron/E Series.