Isn't this just because they will be refreshed soon, rumours are around June. I'd imagine Apple stops making the old hardware a few months before a refresh and then just sells the old stock. Maybe they had shorter contracted orders and/or demand is higher than expected.

Last week I got my (customised) M5 MacBook Pro that was ordered during launch week, not really any longer than expected when ordering a new model.

There was some article today claiming the updated versions won't launch before October.