Trieste Trasporti (local buses) will only provide service between 6am and 9am and between 1pm and 4pm, and APT services (bus G51 to and from Trieste Airport) will be provided between 6am and 9am and between 12pm and 3pm.

For further info:

https://www.triestetrasporti.it/2023/10/usb-sciopero-nazionale-del-trasporto-pubblico-locale-lunedi-9-ottobre-collegamenti-garantiti-tra-le-600-e-le-900-e-tra-le-1300-e-le-1600/