I am not going to type up the whole of the greek this Sunday because there is only one or two unusual features and I dont need to show you the greek to explain them.
Please compare this verse to Luke 14:34 -5 and Mark 9: 50.
How can salt lose its taste? The verb mooranthee is an aorist passive subjunctive form of moorainoo and yes that is related to moron!
So while we say loses its taste in English the verb also means that the salt has been foolish useless distorted and insipid.
Bear in mind at that time salt was valuable and sometimes not stored or prepared perfectly so salt could be spoiled or contaminated?
Look at Luke's version and Mark. Do not obsess on the minor differences such as Luke saying seasons instead of salts.
The idea is the same. Admittedly not obvious in an age when salt can be stored in air and water tight containers. Salt is something precious and valuable that must be prepared and guarded to maintain its value.
The textual differences may simply be due to jesus using the same concept in more than one teaching session?