Did the Buddha teach receivers to be ungrateful? I read the following on the internet:

If you truly understand the practice of generosity, then you'd never
have to look for outright expression of gratitude from the receivers.
The act does and will benefit you in this life and many future lives
to come. It's the donor who should express the gratitude for the
opportunity to build up his great kammic storehouse.

Did the Buddha teach receivers to be ungrateful?
The Buddha taught people (especially monks) to be &quot;worthy of offerings&quot; -- that's in the Saṅghānussati for example, which also says that such a recipient is &quot;worthy of respectful salutations&quot; and  &quot;a field of merit&quot;.
Apparently that (being &quot;worthy of offerings&quot;) does not imply fawning on laypeople in gratitude.
On the subject of fawns though, AN 2.31-32 does talk about gratitude and especially in relation to parents:

Now what is the level of a person of no integrity? A person of no integrity is ungrateful &amp; unthankful. This ingratitude, this lack of thankfulness, is advocated by rude people. It is entirely on the level of people of no integrity. A person of integrity is grateful &amp; thankful. This gratitude, this thankfulness, is advocated by civil people. It is entirely on the level of people of integrity.&quot;
&quot;I tell you, monks, there are two people who are not easy to repay. Which two? Your mother &amp; father. [etc.]