What I find interesting is the OP thinks its worse to be 'shamed' rather than inform people that they are doing something which risks animal welfare and damages the river environment.
Perhaps we should just let people kick dogs rather than shame them for being cruel to animals.
For the record this is what the RSPB say:
www.bbc.co.uk/news/newsbeat-50087990
RSPB tells us in a statement.
"Although ducks and swans can digest all types of bread, too much can leave them feeling full without giving them all of the important vitamins, minerals and nutrients they need."
The RSPB did not know where the poster shared online was put up, or which organisation was behind the campaign.
But like health-conscious humans, it's advised that if you must feed ducks with bread, then you use something other than leftovers from a cheap white loaf.
RSPB England's Twitter account describes granary bread with seeds as "marginally healthier" than white bread, in advice it gave to a concerned wildfowl-feeder.
"Although bread isn't harmful, our advice is to only feed small amounts to birds. We encourage people to use things like sweetcorn, porridge oats and defrosted frozen peas as well as bird seed," adds the RSPB.
HOWEVER too much bread being thrown in one place can affect the biodiversity and pollute the water
canalrivertrust.org.uk/enjoy-the-waterways/canal-and-river-wildlife/keeping-our-ducks-healthy/why-is-bread-bad-for-ducks
Why is bread bad for ducks?
With nearly three-quarters of the population throwing their leftover bread into canals, rivers, reservoirs and lakes every year, find out why it's important for us all to feed ducks differently.
5 reasons why bread is bad
Ducks need a varied diet to be healthy. Bread doesn't have much nutritional value and fills the duck's stomach so that it doesn't forage for foods it would naturally eat, which can lead to malnutrition.
Uneaten soggy bread can cause a build-up of bad nutrients, which can lead to more algae growing around water, more diseases and more pests, such as rats.
Throwing bread into a canal or river can create an unnatural overcrowding of bird populations, as the birds will flock to the same location in search of their starchy treat.
Too many ducks or waterfowl in one place can stress the birds and lead to their habitats being damaged.
This also creates excessive amounts of bird droppings, which, along with being smelly and slippery underfoot, can reduce water quality and clog waterways with harmful algae.
So in summary:
Don't feed them mouldy bread
Don't feed them white bread - feed them granary bread
Don't feed them bread where everyone else does, find a quiet alternative spot
Feed them alternatives to bread
Don't stop feeding ducks
And being told how to feed ducks for the best welfare and for the quality of the water / environment more generally is not 'shaming'
And I'm still not sure what being a single mother has got to do with the price of bread.