If you take your neighbor’s cloak as a pledge, return it by sunset, 27 because that cloak is the only covering your neighbor has. What else can they sleep in? When they cry out to me, I will hear, for I am compassionate.
The sin described here seems to the abuse they have of the poor to add to their idolatry. In their bloated abuse they have no concern about God's anger at all. Instead they make comfy beds to lay on from the multitude of cloaks they have collected under abusive debts. And all this beside little altars they had in their homes or more probably, publicly in the feast halls nearby the public altars. Probably publicly because the next verse has them in the 'house of their idol' drinking wine.
Although there was ritualistic prostitution in temples of Astarte. The Hebrew Bible uses two different words for prostitute, zonah (זנה) and kedeshah (קדשה). The word zonah simply meant an ordinary prostitute. But the word kedeshah literally means consecrated, as a holy prostitute. The context of these verses, where the man and his father are sleeping with the same woman are neither of these. It's just a 'young woman'. Therefore we have no direct indication that 'laying down' here was ritualistic prostitution.
That said, even without direct indication of temple prostitution, I imagine all sorts of fornication, orgies, etc. would have been practiced if the altar was for Astarte. So the verse about father and son sleeping with the same girl, followed by 'laying down' near an altar could associate both verses together and imply ritual temple sex on poor men's cloaks.
I looked at a few commentaries and this does not seem to be the common view. I mean the link with temple sex is not the common view.