True, many times such simple issues often we overlook
I do not think that is the case here.

Sometimes tap water changes can mess with folks.
They add more Chlorine or Copper or etc.....
Or someone uses well water with high Na+ etc.

Some plants might need some adaptation, but you should see signs of decent growth within 1 week for most plants and a good eye can see the change in growth in a few hours/1 day.

Paleness can stem from many issues.
Post a picture might help.

Regards,
Tom Barr