"have learnt about" is a correct and usable phrase in written English.
It is used to talk about something that one has recently come to know or understand. For example, "I have learnt about the importance of eating healthy food."
"We've learnt that a baby should be breastfed within two hours of birth, we have learnt about vaccination.
Perhaps they should have learnt about them earlier.
What is the most important thing you have learnt about leadership?
A key thing I have learnt about being a developer is that it's not at all about memorizing anything.
It will have learnt about him during his life, so it collates all the information gathered and will post according to his patterns".
The lack of candour has now aroused the ire of many who have learnt about it, who see this as a matter of trust - and are not convinced that ISPs are earning that trust.
"I keep telling the students that when they've finished their first robot, they've learnt about electronics, they learnt about logical thinking, they've learnt about programming, mechanics, you've learnt a bit about biology, you've learnt popular science".
"I'll tell you something I've learnt about songwriting, thanks to my wife and daughters.
What has been the best lesson you've learnt about leadership during your career?
Given what we've learnt about Larkin since his death, a figure previously regarded as melancholy and misanthropic has tumbled over in the much less inviting realms of misogyny and racism.
The most fascinating thing I've learnt about Brian is that he's actually a very quiet man, capable of sitting for hours in a trance, gazing at, say, a mountain, and those quiet times are important to him.
