How long have they been in the same pots? And any chance of a photo of the problem

Bay are just about to resprout and have their Spring surge of growth, so it's possible that these are just the old leaves. Evergreens lose their leaves once a year too, just not in autumn. Wait and see what the new growth brings.

Volunteer ...
Could you elaborate on your comment please ?

More you can say about evergreens losing their leaves once a year ... is that usually in the springtime ? Does that apply to almost everything ? Euonymus ? Elaeagus ? Ilex ?

My Pittosporum tobira variegata has lots of leaves turning yellowish and falling off, but also plenty of new greenish shoots sprouting ..

thanks...

Evergreens lose leaves all year round, TT - there may be a few more in Spring as new growth starts to push through, but they shouldn't ever lose lots and lots of leaves at once (except in severe winter conditions).

Thanks Bamboo...
I think maybe my tobira is reacting to the cold of last winter ...
I know of others whose tobira died in the freeze, so I'm lucky mine survived at all ...

The same is happening to my Elaeagnus and Pileostegia viburnoides... they are discarding lots of freeze-damaged leaves and growing new ones... a different style of growing to previous springtimes...

Recovery in action, ain't nature wonderful...

It sure is.... seems that any plant that did get through the winter is growing like crazy to make sure of survival ! :o)