Paint blisters and bubbles right after professional paint job, then rain
I'm not an expert in the chemistry of paint so I did a little research and found this.

As the paint dries at different rates, it begins to pull and contract on one side, and stretch on the other, causing a bubble to form. The other way this can happen is if it rains on paint before it has dried completely.

Bubbles that occur on paint after it rains almost always happen very soon after the paint has been applied, and before it has had a chance to dry properly – often within the first 24 hours, although it could happen up to a week or more after the application.

Ref: https://www.homelogic.co.uk/exterior-paint-bubbling-after-rain-heres-what-to-do

Not sure if this helps but it seems to fit your description.