You might be able to see what lines were changed or added but not deleted. If you have 'STATS ON' and sequence numbers on for the member you are editing, then the sequence numbers on the far right of the screen correspond to the MM values for the member:
VV.MM Version number and modification level. The version number is set
to 1 and the modification level is set to 0 when the member is
created. The modification level is the number of times this version
has been modified. For example, 02.15 means version 2, modification
15. If a member name is just an alternate name for another member, ALIAS appears in this field.
https://www.ibm.com/docs/en/zos/2.2.0?topic=statistics-member-list-display-panel-fields
The standard sequence field is the last 8 characters for fixed-length
records, or the first 8 characters for variable-length records,
regardless of the programming language. Use NUMBER ON STD to generate
sequence numbers in the standard sequence field. For members of
partitioned data sets, the format of standard sequence numbers depends
on whether statistics are being generated. If statistics are being
generated, standard sequence numbers are 6 digits followed by a
2-digit modification level number. The level number flag reflects the
modification level of the member when the line was created or last
changed. If, for example, a sequence number field contains 00040002,
the line was added or last changed at modification level 02. The
sequence number is 000400.
If STATS mode is off, or if you are editing a sequential data set,
standard sequence numbers are 8 digits, right-justified within the
field.
https://www.ibm.com/docs/en/zos/2.1.0?topic=numbers-sequence-number-format-modification-level
So if this is true for the member you are editing, and you want to know what was a changed in the last edit session, then check the Modification level of the member in question in the member display list (you may have to scroll left or right):
            Name     Prompt       Size    Init     Mod      VV MM          ID
 _________ TEST     *Edited          8       7       2      01.02        JOCS065
           **End**  
 
aadn you can see the 00, 01, 02 etc. MM levels in columns 79-80
****** ***************************** Top of Data ******************************
 000100 my data                                                         00010000
 000200 my data                                                         00020000
 000300 my data                                                         00030000
 000400 my data                                                         00040000
 000500 my data                                                         00050000
 000510 more data                                                       00051001
 000600 my changed data                                                 00060002
 000700 my data                                                         00070000
 ****** **************************** Bottom of Data ****************************
so to see only what was last changed (useful in a large dataset), get the MM level (e.g. 45) and then, when editing or viewing, run the commands x all;f '45' 79 all